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The central auditory system encompasses two primary functions: identification and localization. Spatial release from masking (SRM) highlights speech recognition in competing noise and improves the listening experience when a spatial cue is introduced between noise and target speech. This assessment focuses on the integrity of auditory function and holds clinical significance. However, infants or pre-lingual subjects sometimes provide less reliable results. This study investigates the value of cortical auditory evoked potentials (CAEPs) onset and acoustic change complex (ACC) as an objective measurement of SRM. Thirty normal-hearing young adults (11 males) were recruited. We found the spatial separation of signals and noise (±90° symmetrically) resulted in a signal-to-noise ratio (SNR) improvement of 9.00 ± 1.71 dB behaviorally. It significantly enhanced cortical processing at all SNR levels, shortened CAEP latencies, and increased amplitudes, resulting in a greater number of measurable peaks for ACC. SRM showed mild to moderate correlations with the differences between two conditions in CAEP measures. The regression model combining N1′-P2′ amplitude at 5 dB SNR (R2 = 0.26), P1 amplitude at 0 dB SNR (R2 = 0.14), and P1 latency at −5 dB SNR (R2 = 0.15), explained 45.3% of the variance in SRM. Our study demonstrates that introducing spatial cues can improve speech perception and enhance central auditory processing in normal-hearing young adults. CAEPs may contribute to predictions about SRM and hold potential for practical application. NEW & NOTEWORTHY: The neural encoding of spatial release from masking (SRM) can be observed in normal-hearing young adults. Spatial separation between target and masker improves speech perception in noise and enhances central auditory processing. The behavioral results showed mild-to-moderate correlations with electrophysiological measures, with acoustic change complex (ACC) amplitude being a better indicator than onset components. Cortical auditory evoked potentials (CAEPs) may contribute to predictions about spatial release from masking, especially when behavioral tests are less reliable. [ABSTRACT FROM AUTHOR]

Introduction: Aided auditory late latency response (LLR) serves as an objective tool for evaluating auditory cortical maturation following cochlear implantation in children. While aided LLR is commonly measured using sound-field acoustic stimulation, recording electrically evoked LLR (eLLR) offer distinct advantages, such as improved stimulus control and the capability for single electrode stimulation. Hence, the study aimed to compare eLLR responses with single electrode stimulation in the apical, middle, and basal regions and to evaluate their relationship with speech perception in paediatric cochlear implant (CI) recipients. Method: eLLR responses with single electrode stimulation were measured in 27 paediatric unilateral CI users with an active recording electrode placed at Cz. The stimuli consisted of 36 msec biphasic pulse trains presented across three electrode sites (apical-E20, middle-E11, and basal-E03). eLLR responses were compared across these electrode sites, and the relationship between speech recognition scores in quiet and age at implantation with eLLR components was evaluated. Results: eLLR responses were detected in 77 out of 81 tested electrodes of all participants combined (27 for apical, 26 for middle, and 24 for basal stimulation). There were no significant differences in P1, N1 latencies and P1 amplitude across electrode site. However, significantly larger N1 and P1-N1 amplitudes were observed for apical stimulations compared to basal stimulations. No differences in N1 amplitude were found between middle and apical stimulations, and the P1-N1 amplitude was significantly larger for middle compared to basal electrode stimulation, with no difference between the apical and middle electrodes stimulation. A moderate positive correlation was present between speech recognition scores in quiet and both N1, P1-N1 amplitudes for apical stimulation. Age at implantation was negatively correlated with N1 amplitude for the apical and P1-N1 amplitude for basal stimulation. Discussion: eLLR responses could be elicited in majority of paediatric CI users across electrode sites. Variations in eLLR responses across electrode sites suggest disparities in auditory cortical maturation. The findings underscore the significance of the N1 biomarker in evaluating higher-order auditory cortical development. Therefore, utilizing eLLR with single electrode stimulation may serve as a valuable tool for assessing post-cochlear implantation maturational changes in paediatric populations. [ABSTRACT FROM AUTHOR]

Abstract Background Cortical auditory evoked potentials (CAEPs) display both auditory processing and neurological activity in the auditory cortex. The purpose of this research is to evaluate the importance of CAEPs in identifying auditory processing disorders in patients with peripheral neuropathy (PN) in different pathologies. Sixty cases with PN of different pathologies represented the study group which was classified into two subgroups according to the underlying pathology of PN: those with either axonal PN (44 patients) and those with demyelinating PN (16 patients). The current study also included a control group of 40 healthy volunteers who did not have any peripheral or central auditory neurological disorders. CAEPs were recorded in both groups. Results The study group’s CAEP response showed significantly delayed latencies than the control groups. Comparing the two study subgroups revealed that the axonal PN group had significant delayed latencies of N1 and P2 components in comparison to the demyelinating PN group. Conclusion Cortical auditory evoked potentials can be used efficiently to diagnosis central auditory processing disorders in patients with PN. CAEP latencies can be employed alone or in conjunction with amplitudes; however, CAEP latencies are more significant than amplitudes for such purpose. Both demyelinating and axonal PN are associated with impaired auditory processing; however, axonal PN patients are more likely to be affected, suggesting that axonal PN has a significantly drastic effect on the central auditory nervous system.

Background: Cortical auditory evoked potentials (CAEPs) display both auditory processing and neurological activity in the auditory cortex. The purpose of this research is to evaluate the importance of CAEPs in identifying auditory processing disorders in patients with peripheral neuropathy (PN) in different pathologies. Sixty cases with PN of different pathologies represented the study group which was classified into two subgroups according to the underlying pathology of PN: those with either axonal PN (44 patients) and those with demyelinating PN (16 patients). The current study also included a control group of 40 healthy volunteers who did not have any peripheral or central auditory neurological disorders. CAEPs were recorded in both groups. Results: The study group's CAEP response showed significantly delayed latencies than the control groups. Comparing the two study subgroups revealed that the axonal PN group had significant delayed latencies of N1 and P2 components in comparison to the demyelinating PN group. Conclusion: Cortical auditory evoked potentials can be used efficiently to diagnosis central auditory processing disorders in patients with PN. CAEP latencies can be employed alone or in conjunction with amplitudes; however, CAEP latencies are more significant than amplitudes for such purpose. Both demyelinating and axonal PN are associated with impaired auditory processing; however, axonal PN patients are more likely to be affected, suggesting that axonal PN has a significantly drastic effect on the central auditory nervous system. [ABSTRACT FROM AUTHOR]

Simple Summary: Many individuals report difficulty perceiving speech in background noise. Research has shown that one factor in this type of processing is the effect of noise on the brain's response to speech. Different types of noise affect the strength of the neural encoding of speech to varying degrees, with greater informational masking causing greater degradation. Previous research has focused on the effects of attention in noise, which tends to enhance the neural encoding of the speech signal via inhibitory mechanisms. However, there is a pre-attentive stage of inhibition, sensory gating, which has been linked to speech perception in noise. The impact of noise on the neural response during this phase remains unclear. This preliminary study investigated the gating response, recorded via high-density EEG in fifteen normal-hearing adults, in quiet and noise conditions with low and high informational masking. Scalp maps were generated to observe brain activation in each condition. Significant gating occurred in quiet, while noise conditions resulted in a significantly decreased gating response. The gating function was significantly degraded in noise with less informational masking content, coinciding with a reduced activation of inhibitory gating networks. These findings illustrate the adverse effect of noise on pre-attentive inhibition related to speech perception. Cortical auditory evoked potentials (CAEPs) indicate that noise degrades auditory neural encoding, causing decreased peak amplitude and increased peak latency. Different types of noise affect CAEP responses, with greater informational masking causing additional degradation. In noisy conditions, attention can improve target signals' neural encoding, reflected by an increased CAEP amplitude, which may be facilitated through various inhibitory mechanisms at both pre-attentive and attentive levels. While previous research has mainly focused on inhibition effects during attentive auditory processing in noise, the impact of noise on the neural response during the pre-attentive phase remains unclear. Therefore, this preliminary study aimed to assess the auditory gating response, reflective of the sensory inhibitory stage, to repeated vowel pairs presented in background noise. CAEPs were recorded via high-density EEG in fifteen normal-hearing adults in quiet and noise conditions with low and high informational masking. The difference between the average CAEP peak amplitude evoked by each vowel in the pair was compared across conditions. Scalp maps were generated to observe general cortical inhibitory networks in each condition. Significant gating occurred in quiet, while noise conditions resulted in a significantly decreased gating response. The gating function was significantly degraded in noise with less informational masking content, coinciding with a reduced activation of inhibitory gating networks. These findings illustrate the adverse effect of noise on pre-attentive inhibition related to speech perception. [ABSTRACT FROM AUTHOR]

IntroductionAided auditory late latency response (LLR) serves as an objective tool for evaluating auditory cortical maturation following cochlear implantation in children. While aided LLR is commonly measured using sound-field acoustic stimulation, recording electrically evoked LLR (eLLR) offer distinct advantages, such as improved stimulus control and the capability for single electrode stimulation. Hence, the study aimed to compare eLLR responses with single electrode stimulation in the apical, middle, and basal regions and to evaluate their relationship with speech perception in paediatric cochlear implant (CI) recipients.MethodeLLR responses with single electrode stimulation were measured in 27 paediatric unilateral CI users with an active recording electrode placed at Cz. The stimuli consisted of 36 msec biphasic pulse trains presented across three electrode sites (apical-E20, middle-E11, and basal-E03). eLLR responses were compared across these electrode sites, and the relationship between speech recognition scores in quiet and age at implantation with eLLR components was evaluated.ResultseLLR responses were detected in 77 out of 81 tested electrodes of all participants combined (27 for apical, 26 for middle, and 24 for basal stimulation). There were no significant differences in P1, N1 latencies and P1 amplitude across electrode site. However, significantly larger N1 and P1-N1 amplitudes were observed for apical stimulations compared to basal stimulations. No differences in N1 amplitude were found between middle and apical stimulations, and the P1-N1 amplitude was significantly larger for middle compared to basal electrode stimulation, with no difference between the apical and middle electrodes stimulation. A moderate positive correlation was present between speech recognition scores in quiet and both N1, P1-N1 amplitudes for apical stimulation. Age at implantation was negatively correlated with N1 amplitude for the apical and P1-N1 amplitude for basal stimulation.DiscussioneLLR responses could be elicited in majority of paediatric CI users across electrode sites. Variations in eLLR responses across electrode sites suggest disparities in auditory cortical maturation. The findings underscore the significance of the N1 biomarker in evaluating higher-order auditory cortical development. Therefore, utilizing eLLR with single electrode stimulation may serve as a valuable tool for assessing post-cochlear implantation maturational changes in paediatric populations.

Purpose:The use of objective electrophysiological tests of hearing with the approaches of threshold estimation, otoneurology diagnosis, as well as evaluating the usefulness of hearing prostheses, including hearing aids and cochlear implants, have been of interest to clinicians and researchers in the field of hearing sciences since the beginning. Among the existing objective hearing tests, the recording of auditory late responses (ALRs) is a sign of detecting auditory stimuli in the auditory cortical areas and provides information on the correct functioning of the cortical and subcortical auditory areas. This information cannot be obtained using objective and routine tests such as auditory brainstem responses (ABRs). The purpose of the present study is to review the practical and multiple approaches of this tool in the test battery approach in order to evaluate the hearing system of children and adults and the usefulness of rehabilitation in hearing impaired individuals.Methods:This study is a narrative review and searches for sources using the keywords "cortical auditory evoked potentials", "auditory late responses", "N1-P2", "hearing aids", "cochlear implantation", "auditory training", and "auditory threshold" between the period of 2000 and 2023 in Google Scholar, PubMed, SID, and Magiran databases were performed.Results:Among the studies found, duplicates were removed and those with available full text were used in this study. By evaluating the results obtained from them, the use of ALRs in estimating the hearing threshold of children and adults is confirmed, and this test can be used to evaluate the usefulness of the chosen rehabilitation strategy, including hearing aid, cochlear implantation, and auditory training.Conclusion:The study showed that ALRs are a useful tool for evaluating the cortical auditory areas and can, along with other electrophysiological hearing tests such as ABRs, provide more awareness in a wider range of the auditory system, especially for diagnostic approaches and evaluation of the usefulness of rehabilitation interventions, especially at a young age, for therapists.

Cortical auditory evoked potentials (CAEPs) indicate that noise degrades auditory neural encoding, causing decreased peak amplitude and increased peak latency. Different types of noise affect CAEP responses, with greater informational masking causing additional degradation. In noisy conditions, attention can improve target signals’ neural encoding, reflected by an increased CAEP amplitude, which may be facilitated through various inhibitory mechanisms at both pre-attentive and attentive levels. While previous research has mainly focused on inhibition effects during attentive auditory processing in noise, the impact of noise on the neural response during the pre-attentive phase remains unclear. Therefore, this preliminary study aimed to assess the auditory gating response, reflective of the sensory inhibitory stage, to repeated vowel pairs presented in background noise. CAEPs were recorded via high-density EEG in fifteen normal-hearing adults in quiet and noise conditions with low and high informational masking. The difference between the average CAEP peak amplitude evoked by each vowel in the pair was compared across conditions. Scalp maps were generated to observe general cortical inhibitory networks in each condition. Significant gating occurred in quiet, while noise conditions resulted in a significantly decreased gating response. The gating function was significantly degraded in noise with less informational masking content, coinciding with a reduced activation of inhibitory gating networks. These findings illustrate the adverse effect of noise on pre-attentive inhibition related to speech perception.

A long-standing observation is that the Mismatch Response (MMR) has the potential to offer a clinically feasible index of sound discrimination. However, findings that positively identify MMRs at the individual level have been mixed, even for those who are normally hearing and who can discriminate sounds behaviourally. This complicates interpretation when an MMR is not observed. The objective of this study was to determine the reliability of the MMR using an optimised paradigm and a range of stimuli relevant to audiological applications in relation to objective verification of hearing aid fittings. MMRs were measured using an optimised 3-deviant paradigm in response to a range of sounds designed for aided and unaided sound field assessments, including complex tones (CTs) and speech-like signals. Seventeen normally hearing adults (18–56 years). The most robust MMRs were recorded in response to CTs; responses were positively identified in 50 out of 51 instances (98%), assessed via objective Hotelling's T2 bias-free statistical analyses. The results indicate that CTs in conjunction with optimised recording and analysis parameters offer the potential to elicit robust MMRs, supporting future utilisation of MMRs for clinical audiological applications. [ABSTRACT FROM AUTHOR]

Objectives The objective assessment tests overcome the variability of subjective methods. Cortical recordings with gap pre-pulse inhibition of the acoustic startle reflex stimulus have been used as objective tinnitus assessments in humans. This study aims to investigate this possible objective tinnitus test and compare gap-induced inhibition in different stimulus parameters and brain regions. Materials & Methods Twenty People (18-50 years old) without hearing loss and tinnitus were included. The sound stimuli consisted of continuous background noise with a loud startle tone preceded by a silent gap (20 and 40 ms duration, 120 and 150 ms distance from the startle). The N1-P2 complex amplitude and topoplot maps were extracted in 27-channel cortical response recording after signal processing. Four brain regions of interest (ROI) of anterio-frontal, centro-frontal, right, and left temporal were investigated. Results The results showed that the maximum inhibition occurred in a 40 ms gap duration and 150 ms distance in all 4 ROIs. In comparing ROIs, the centro-frontal and left temporal regions revealed the most inhibition (p<0.05). The decrease in the amplitude of the N1 and P2 in that region could also be traced in the 100 and 200 ms topoplots. Conclusion Gap-induced inhibition was observed in all gap-embedded stimuli and all ROIs. However, the 40-150 mode and centro-frontal and left temporal regions had maximum inhibition in normal subjects. It provides a promising tool for objectively assessing tinnitus in humans with particular implications in children. [ABSTRACT FROM AUTHOR]

Background: Among individuals with vestibular dysfunction, the loss of vestibular sensory information is found to alter cognitive abilities that coordinate spatial and non-spatial information. P300 is an event-related potential commonly used to assess cognitive processing. The aim of the present study was to compare the latency and amplitude of cortical auditory evoked potential and P300 between individuals with vestibular dysfunction and individuals with no vestibular dysfunction. Methods: Forty adults with a mean age of 40.5 ± 13.07 participated in the study. Group I included 20 adults diagnosed with vestibular dysfunction and group II included 20 age-matched adults with no vestibular dysfunction. The P300 was recorded from the electrode site Cz and Pz. It was elicited using pure-tones in odd-ball paradigm. The latency and amplitude of peaks P1, N1, P2, and N2 of the cortical auditory evoked potential and the P300 were measured. Results: Significant amplitude difference was observed in cortical potentials at Cz and Pz. The P300 was present only in 70% of individuals with vestibular dysfunction compared to 100% among individuals with no vestibular dysfunction. The mean amplitude of the P300 was slightly larger in group 1 compared to group 2 and the mean latency of the P300 was similar in both groups. However, the difference in amplitude of the P300 between groups was not statistically significant. Conclusions: Knowing the cognitive function of individuals with vestibular dysfunction enables planning vestibular rehabilitation therapy, which enhances the quality of life in these individuals by improving their vestibular and cognitive functions.

Acoustic Change Complex (ACC) is a cortical auditory evoked potential elicited in response to a change in an ongoing sound. Since it is supposed to reflect auditory discrimination at the cortical level, recording of this potential has recently gained much attention. From a technical standpoint, the stimulus used should be long enough to accommodate the needed change. This research addresses the development and standardization of short duration tonal stimuli which can be implemented in most of the Evoked Potential (EP) equipment used in regular Audiology clinics. Short duration tonal stimuli (500 msec.) were generated and edited using Audacity software. Temporal change was done using gap-in-tones stimuli (6, 10, 30 and 50 msec. in 1000 Hz tone). Frequency change was represented by frequency pairs (2%, 4%, 10% and 25% change from 1000 Hz base frequency). The developed stimuli were then used to generate ACC potential in 41 normal hearing children ranging in age from 2 to 10 years. A comparison was held between ACC response recorded using the different stimuli in reference to percent identifiability, morphology, latency and amplitude measures. Gap-in-tones at 10 msec. and 4% frequency change could elicit ACC response in 100% of subjects. ACC had the same morphology of the onset response in the majority of subjects, with longer latency and smaller amplitude. ACC amplitude was consistently affected by magnitude of change. ACC was successfully recorded in 100% of normal hearing children using the developed short duration tonal stimuli for temporal change (10 msec.) and frequency change (4%). These stimuli can be uploaded in clinical EP equipment. ACC amplitude could be a better indicator of cortical discrimination compared to latency. [ABSTRACT FROM AUTHOR]

Differences in the timing and intensity of sounds arriving at the two ears provide fundamental binaural cues that help us localize and segregate sounds in the environment. Neural encoding of these cues is commonly represented asymmetrically in the cortex with stronger activation in the hemisphere contralateral to the perceived spatial location. Although advancing age is known to degrade the perception of binaural cues, less is known about how the neural representation of such cues is impacted by age. Here, we use electroencephalography (EEG) to investigate age-related changes in the hemispheric distribution of interaural time difference (ITD) encoding based on cortical auditory evoked potentials (CAEPs) and derived binaural interaction component (BIC) measures in ten younger and ten older normalhearing adults. Sensor-level analyses of the CAEP and BIC showed age-related differences in global field power, where older listeners had significantly larger responses than younger for both binaural metrics. Source-level analyses showed hemispheric differences in auditory cortex activity for left and right lateralized stimuli in younger adults, consistent with a contralateral activation model for processing ITDs. Older adults, however, showed reduced hemispheric asymmetry across ITDs, despite having overall larger responses than younger adults. Further, when averaged across ITD condition to evaluate changes in cortical asymmetry over time, there was a significant shift in laterality corresponding to the peak components (P1, N1, P2) in the source waveform that also was affected by age. These novel results demonstrate across-hemisphere cortical dynamics during binaural temporal processing that are altered with advancing age. [ABSTRACT FROM AUTHOR]

• Cortical plasticity is evident in children with unilateral hearing loss rehabilitated by a hearing aid. • Functional binaural pathways can develop in children with unilateral hearing loss using a hearing aid. • Binaural processing manifested in a cortical binaural interaction biomarker. • Cortical potentials provide information on auditory function with a hearing aid. • P1 potential is sensitive to eliciting stimulus acoustics' and amplification characteristics. Congenital or early-onset unilateral hearing loss (UHL) can disrupt the normal development of the auditory system. In extreme cases of UHL (i.e., single sided deafness), consistent cochlear implant use during sensitive periods resulted in cortical reorganization that partially reversed the detrimental effects of unilateral sensory deprivation. There is a gap in knowledge, however, regarding cortical plasticity i.e. the brain's capacity to adapt, reorganize, and develop binaural pathways in milder degrees of UHL rehabilitated by a hearing aid (HA). The current study was set to investigate early-stage cortical processing and electrophysiological manifestations of binaural processing by means of cortical auditory evoked potentials (CAEPs) to speech sounds, in children with moderate to severe-to-profound UHL using a HA. Fourteen children with UHL (CHwUHL), 6-14 years old consistently using a HA for 3.5 (±2.3) years participated in the study. CAEPs were elicited to the speech sounds /m/, /g/, and /t/ in three listening conditions: monaural [Normal hearing (NH), HA], and bilateral [BI (NH + HA)]. Results indicated age-appropriate CAEP morphology in the NH and BI listening conditions in all children. In the HA listening condition: (1) CAEPs showed similar morphology to that found in the NH listening condition, however, the mature morphology observed in older children in the NH listening condition was not evident; (2) P1 was elicited in all but two children with severe-to-profound hearing loss, to at least one speech stimuli, indicating effective audibility; (3) A significant mismatch in timing and synchrony between the NH and HA ear was found; (4) P1 was sensitive to the acoustic features of the eliciting stimulus and to the amplification characteristics of the HA. Finally, a cortical binaural interaction component (BIC) was derived in most children. In conclusion, the current study provides first-time evidence for cortical plasticity and partial reversal of the detrimental effects of moderate to severe-to-profound UHL rehabilitated by a HA. The derivation of a cortical biomarker of binaural processing implies that functional binaural pathways can develop when sufficient auditory input is provided to the affected ear. CAEPs may thus serve as a clinical tool for assessing, monitoring, and managing CHwUHL using a HA. [ABSTRACT FROM AUTHOR]

• Cortical Auditory Evoked Potentials (CAEPs) measured in normal hearing (NH) listeners and bimodal cochlear implant (CI) users. • Time-frequency analysis of CAEPs as a tool to investigate integration. • Interaural temporal mismatch resulted in reduced N1 amplitude and phase locking value in NH listeners. • CAEPs offer a means to estimate cortical delay between electric and acoustic stimulation in bimodal individuals. • Correcting individual temporal interaural mismatch in bimodal CI users led to an increase in N1 amplitude. • Limited phase locking increase suggests constrained electric-acoustic cortical integration. Combining a cochlear implant with contralateral acoustic hearing typically enhances speech understanding, although this improvement varies among CI users and can lead to an interference effect. This variability may be associated with the effectiveness of the integration between electric and acoustic stimulation, which might be affected by the temporal mismatch between the two listening sides. Finding methods to compensate for the temporal mismatch might contribute to the optimal adjustment of bimodal devices and to improve hearing in CI users with contralateral acoustic hearing. The current study investigates cortical auditory evoked potentials (CAEPs) in normal hearing listeners (NH) and CI users with contralateral acoustic hearing. In NH, the amplitude of the N1 peak and the maximum phase locking value (PLV) were analyzed under monaural, binaural, and binaural temporally mismatched conditions. In CI users, CAEPs were measured when listening with CI only (CIS_only), acoustically only (AS_only) and with both sides together (CIS+AS). When listening with CIS+AS, various interaural delays were introduced between the electric and acoustic stimuli. In NH listeners, interaural temporal mismatch resulted in decreased N1 amplitude and PLV. Moreover, PLV is suggested as a more sensitive measure to investigate the integration of information between the two listening sides. CI users showed varied N1 latencies between the AS_only and CIS_only listening conditions, with increased N1 amplitude when the temporal mismatch was compensated. A tendency towards increased PLV was also observed, however, to a lesser extent than in NH listeners, suggesting a limited integration between electric and acoustic stimulation. This work highlights the potential of CAEPs measurement to investigate cortical processing of the information between two listening sides in NH and bimodal CI users. [ABSTRACT FROM AUTHOR]

Differences in the timing and intensity of sounds arriving at the two ears provide fundamental binaural cues that help us localize and segregate sounds in the environment. Neural encoding of these cues is commonly represented asymmetrically in the cortex with stronger activation in the hemisphere contralateral to the perceived spatial location. Although advancing age is known to degrade the perception of binaural cues, less is known about how the neural representation of such cues is impacted by age. Here, we use electroencephalography (EEG) to investigate age-related changes in the hemispheric distribution of interaural time difference (ITD) encoding based on cortical auditory evoked potentials (CAEPs) and derived binaural interaction component (BIC) measures in ten younger and ten older normal-hearing adults. Sensor-level analyses of the CAEP and BIC showed age-related differences in global field power, where older listeners had significantly larger responses than younger for both binaural metrics. Source-level analyses showed hemispheric differences in auditory cortex activity for left and right lateralized stimuli in younger adults, consistent with a contralateral activation model for processing ITDs. Older adults, however, showed reduced hemispheric asymmetry across ITDs, despite having overall larger responses than younger adults. Further, when averaged across ITD condition to evaluate changes in cortical asymmetry over time, there was a significant shift in laterality corresponding to the peak components (P1, N1, P2) in the source waveform that also was affected by age. These novel results demonstrate across-hemisphere cortical dynamics during binaural temporal processing that are altered with advancing age.

Introduction: The common mechanism of tinnitus, hyperacusis, and loudness perception is hypothesized to be related to central gain. Although central gain increases with attempts to compensate hearing loss, reduced input can also be observed in those with clinically normal hearing. This study aimed to evaluate the loudness growth function of tinnitus patients with and without hyperacusis using behavioural and electrophysiological methods. Methods: The study consists of three groups with a total of 60 clinically normal hearing subjects, including the control group (10 men and 10 women; mean age 39.8, SD 11.8 years), tinnitus group (10 men and 10 women; mean age 40.9, SD 12.2 years), and hyperacusis group (also have tinnitus) (7 men and 13 women; mean age 38.7, SD 14.6 years). Loudness discomfort levels (LDLs), categorical loudness scaling (CLS), and cortical auditory evoked potentials were used for the evaluation of loudness growth. N1-P2 component amplitudes and latencies were measured. Results: LDL results of 500, 1,000, 2,000, 4,000, and 8,000 Hz showed a significant difference between the hyperacusis group and the other two groups (p < 0.001). In the loudness scale test performed with 500 Hz and 2,000 Hz narrow-band noise (NBN) stimulus, a significant difference was observed between the hyperacusis group and the other two groups in the "medium," "loud," and "very loud" categories (p < 0.001). In the cortical examination performed with 500 Hz and 2,000 Hz NBN stimulus at 40, 60, and 80 dB nHL intensities, no significant difference was observed between the groups in the N1, P2 latency, and N1-P2 peak-to-peak amplitude. Conclusion: Although the hyperacusis group is significantly different between groups in behavioural tests, the same cannot be said for electrophysiological tests. In our attempt to differentiate tinnitus and hyperacusis with electrophysiological tests over the loudness growth function, N1 and P2 responses were not seen as suitable methods. However, it appears to be beneficial to use CLS in addition to LDLs in behavioural tests. [ABSTRACT FROM AUTHOR]

Background The masking-level difference (MLD) can be measured via voluntary behavioral responses (voluntary behavioral MLD [vMLD]) and/or via electrophysiological cortical auditory evoked potentials (CAEPs; electrophysiological MLD [eMLD]). It may be possible to enhance the ecologic validity of the MLD by using nonsense-syllable speech stimuli. Purpose The aim of this study is to determine the feasibility of measuring both the vMLD and eMLD with speech stimuli. The study also investigates whether certain nonsense-syllable stimuli (/α/, /dα/, /di/, /tα/, /wα/) may be more useful than others in measuring both the vMLD and eMLD. Research Design This is a descriptive feasibility pilot study. Study Sample Seventeen young adults (age range 19–26 years; 15 women) with hearing thresholds of 0.25–8.0 kHz ≤ 25 dB HL, bilaterally, were recruited. Data Collection and Analysis Behavioral and electrophysiological MLDs were measured with similar methods. The MLD was defined as SoNo – SπNo thresholds. Stimuli were natural-sounding nonsense syllables (/α/, /dα/, /di/, /tα/, /wα/), which were presented in 65 dB HL continuous speech-weighted noise. The eMLD was measured with the CAEP P2. Group means, standard deviations, and distributions were presented. The feasibility of using nonsense syllables was evaluated by considering whether measurable vMLDs and eMLDs were produced. Useful nonsense syllables produced vMLDs and eMLDs with (1) comparatively large mean magnitudes, (2) few negligible MLDs, and (3) distributions with adequate spread and few extreme values. Results The stimuli /α/ (6.0 [1.9]) and /wα/ (7.5 [1.3]) produced vMLDs with the highest average magnitudes, with no vMLDs of 0 dB and with adequate spread. The stimulus /α/ produced eMLDs with the highest average magnitude (9.6 [2.8]), no eMLDs of 0 dB and adequate spread, whereas the stimulus /wα/ produced eMLDs with an adequate magnitude (6.9 [3.9]), no MLDs of 0 dB, but with a right-skewed distribution and an extreme value. The other stimuli produced vMLDs with low mean magnitudes and several vMLDs of 0 dB. Conclusion These pilot data support the feasibility of using nonsense syllables to record vMLDs and eMLDs. The stimulus /α/ appeared most useful for both behavioral and electrophysiological modalities. Differences in MLDs across modalities may be attributed to low-level audibility of some high-frequency components of the stimuli. [ABSTRACT FROM AUTHOR]

Background: Vestibular dysfunction is known to affect cognitive abilities related to the processing of spatial and non-spatial information. P300 is an event-related potential (ERP) used to assess cognitive function. Studies have shown abnormalities in P300 in individuals with vestibular hypofunction. However, the literature shows equivocal findings for P300 in individuals with vestibular dysfunction. The aim of present study was to compare the latency and amplitude of cortical auditory evoked potential and P300 between individuals with vestibular dysfunction and individuals with no vestibular dysfunction. Methods: Forty adults with a mean age of 40.5 years participated in the study. Group I included 20 adults diagnosed with vestibular dysfunction and group II included 20 age-matched adults with no vestibular dysfunction. The P300 was recorded using pure-tones in an odd-ball paradigm, from electrode sites Cz and Pz. The latency and amplitude of peaks P1, N1, P2, N2 P300, and N4 were measured. Results: The results showed no significant difference in the latency and amplitude of peaks P1, N1, P2, and N2 of the cortical auditory potentials between groups. The P300 was absent in approximately 30% of individuals with vestibular dysfunction meanwhile, it was present in all individuals in group II. The mean latency and amplitude of the P300 and latency of N4 were not significantly different between the groups. However, a significant difference was observed in N4 amplitude between groups at both electrode sites. And, no correlation was observed between the DHI score and the P300 parameters in group I. Conclusions: the P300 was absent in a greater number of individuals with vestibular dysfunction, suggesting cognitive impairment. However, when the P300 was present the peak latency and amplitude showed no significant difference in both groups.

Background: Among individuals with vestibular dysfunction, the loss of vestibular sensory information is found to alter cognitive abilities that coordinate spatial and non-spatial information. P300 is an event-related potential commonly used to assess cognitive processing. The aim of the present study was to compare the latency and amplitude of cortical auditory evoked potential and P300 between individuals with vestibular dysfunction and individuals with no vestibular dysfunction. Methods: Forty adults with a mean age of 40.5 ± 13.07 participated in the study. Group I included 20 adults diagnosed with vestibular dysfunction and group II included 20 age-matched adults with no vestibular dysfunction. The P300 was recorded from the electrode site Cz and Pz. It was elicited using pure-tones in odd-ball paradigm. The latency and amplitude of peaks P1, N1, P2, and N2 of the cortical auditory evoked potential and the P300 were measured. Results: Significant amplitude difference was observed in cortical potentials at Cz and Pz. The P300 was present only in 70% of individuals with vestibular dysfunction compared to 100% among individuals with no vestibular dysfunction. The mean amplitude of the P300 was slightly larger in group 1 compared to group 2 and the mean latency of the P300 was similar in both groups. However, the difference in amplitude of the P300 between groups was not statistically significant. Conclusions: Knowing the cognitive function of individuals with vestibular dysfunction enables planning vestibular rehabilitation therapy, which enhances the quality of life in these individuals by improving their vestibular and cognitive functions.

Introduction: Benefits of bilateral cochlear implants (CI) may be compromised by delays to implantation of either ear. This study aimed to evaluate the effects of sequential bilateral CI use in children who received their first CI at young ages, using a clinical set-up. Methods: One-channel cortical auditory evoked potentials and speech perception in quiet and noise were evoked at repeated times (0, 3, 6, 12 months of bilateral CI use) by unilateral and bilateral stimulation in 28 children with early-onset deafness. These children were unilaterally implanted before 3.69 years of age (mean ± SD of 1.98 ± 0.73 years) and received a second CI after 5.13 ± 2.37 years of unilateral CI use. Comparisons between unilaterally evoked responses were used to measure asymmetric function between the ears and comparisons between bilateral responses and each unilateral response were used to measure the bilateral benefit. Results: Chronic bilateral CI promoted changes in cortical auditory responses and speech perception performance; however, large asymmetries were present between the two unilateral responses despite ongoing bilateral CI use. Persistent cortical differences between the two sides at 1 year of bilateral stimulation were predicted by increasing age at the first surgery and inter-implant delay. Larger asymmetries in speech perception occurred with longer inter-implant delays. Bilateral responses were more similar to the unilateral responses from the first rather than the second CI. Conclusion: These findings are consistent with the development of the aural preference syndrome and reinforce the importance of providing bilateral CIs simultaneously or sequentially with very short delays. [ABSTRACT FROM AUTHOR]

Age-related hearing loss is one of the most prevalent health conditions in older adults. Although hearing aid technology has advanced dramatically, a large percentage of older adults do not use hearing aids. This untreated hearing loss may accelerate declines in cognitive and neural function and dramatically affect the quality of life. Our previous findings have shown that the use of hearing aids improves cortical and cognitive function and offsets subcortical physiological decline. The current study tested the time course of neural adaptation to hearing aids over the course of 6 months and aimed to determine whether early measures of cortical processing predict the capacity for neural plasticity. Seventeen (9 females) older adults (mean age = 75 years) with age-related hearing loss with no history of hearing aid use were fit with bilateral hearing aids and tested in six testing sessions. Neural changes were observed as early as 2 weeks following the initial fitting of hearing aids. Increases in N1 amplitudes were observed as early as 2 weeks following the hearing aid fitting, whereas changes in P2 amplitudes were not observed until 12 weeks of hearing aid use. The findings suggest that increased audibility through hearing aids may facilitate rapid increases in cortical detection, but a longer time period of exposure to amplified sound may be required to integrate features of the signal and form auditory object representations. The results also showed a relationship between neural responses in earlier sessions and the change predicted after 6 months of the use of hearing aids. This study demonstrates rapid cortical adaptation to increased auditory input. Knowledge of the time course of neural adaptation may aid audiologists in counseling their patients, especially those who are struggling to adjust to amplification. A future comparison of a control group with no use of hearing aids that undergoes the same testing sessions as the study's group will validate these findings. [ABSTRACT FROM AUTHOR]

Age-related hearing loss is one of the most prevalent health conditions in older adults. Although hearing aid technology has advanced dramatically, a large percentage of older adults do not use hearing aids. This untreated hearing loss may accelerate declines in cognitive and neural function and dramatically affect the quality of life. Our previous findings have shown that the use of hearing aids improves cortical and cognitive function and offsets subcortical physiological decline. The current study tested the time course of neural adaptation to hearing aids over the course of 6 months and aimed to determine whether early measures of cortical processing predict the capacity for neural plasticity. Seventeen (9 females) older adults (mean age = 75 years) with age-related hearing loss with no history of hearing aid use were fit with bilateral hearing aids and tested in six testing sessions. Neural changes were observed as early as 2 weeks following the initial fitting of hearing aids. Increases in N1 amplitudes were observed as early as 2 weeks following the hearing aid fitting, whereas changes in P2 amplitudes were not observed until 12 weeks of hearing aid use. The findings suggest that increased audibility through hearing aids may facilitate rapid increases in cortical detection, but a longer time period of exposure to amplified sound may be required to integrate features of the signal and form auditory object representations. The results also showed a relationship between neural responses in earlier sessions and the change predicted after 6 months of the use of hearing aids. This study demonstrates rapid cortical adaptation to increased auditory input. Knowledge of the time course of neural adaptation may aid audiologists in counseling their patients, especially those who are struggling to adjust to amplification. A future comparison of a control group with no use of hearing aids that undergoes the same testing sessions as the study’s group will validate these findings.

Objective: The objective of the study is to establish normative values of cortical evoked response audiometry (CERA) in a heterogeneous Indian population and correlate CERA threshold with pure tone audiometric (PTA) threshold values. Materials and Methods: A prospective study was carried out on 31 volunteers (n = 62) who had no otological or neurological complaints. Two study groups were formed; Group 1 with individuals from 20 to 40 years (mean age of 29.1 years) and Group 2 with individuals from 41 to 60 years (mean age of 46.2 years). The latencies and amplitudes of the waves of P1, N1, and P2 at threshold and 70 dBnHL were measured. Results: Twenty-nine participants (94% of the ears) had CERA threshold within 20 dB of true behavioral threshold with only 6% having a difference of >20 dB with their PTA thresholds. There was a significant difference (P < 0.05) at 70 dB in amplitudes for waves P1, N1, and P2 at 2 kHz and additionally at 1 kHz for N1 between the two groups. Conclusion: Normative values for CERA in a heterogeneous Indian population at 70 dB nHL using tone burst stimulus was found to have an average latency of 46.5, 90.1, and 155.5 ms for P1, N1, and P2, respectively. The average amplitude of P1 at 70 dB nHL was 4.3 μV, N1, was 6.5 μV and P2 was 3.2 μV. Hearing threshold obtained with CERA gave a good indication of the actual behavioral hearing threshold of the normal controls, and the age of an individual had a significant effect on the values obtained during CERA testing with N1 being significantly larger at 1 kHz and 2 kHz in older adults when compared to young adults.

Background and Objectives: Tinnitus is a complex condition that varies in loudness, quality, location, and distress. Different definitions, heterogeneity, and lack of objective measuring have challenged the understanding the mechanisms involved and definitive cure. The integrative model correlates each of these characteristics to separate parallel and overlapping subnetworks that process tinnitus’s perception and emotional reaction. Many of these networks are common with the gap pre-pulse inhibition of acoustic startle (GPIAS) neural circuity. GPIAS, which measures tinnitus in animals, has recently been used for humans with various recording methods. The present study aimed to review the evidence achieved with gap stimuli in patients with tinnitus to support the potential of cortical responses recorded with the GPIAS stimulus and to objectively detect tinnitus in humans. Methods: Studies were identified by searching electronic databases with relevant keywords. Results: The role of the auditory cortex in processing short gaps, the possibility of evaluating the gap detection ability with GPIAS, and the advantage of cortical responses in reflecting both stimulus properties and different aspects of tinnitus emphasize the importance of this issue. The results of most studies have proven the gap detection deficiency in tinnitus. However, the validity of the auditory startle reflex still needs to be verified due to the inherent variability and different methods. Conclusion: Further human studies are recommended because the perception of tinnitus can be controlled. An appealing research line in this area is multi-channel cortical evoked potentials. Defects of GPIAS with cortical recording can indicate tinnitus.

Objective. This study aimed to investigate age-related changes in cortical auditory evoked potentials (CAEPs) while considering three crucial factors: aging, high-frequency hearing loss and sensation level of the CAEP stimulus. Method. The electrophysiological and audiometric data of 71 elderly participants were analyzed using multiple regression analysis to investigate the association of CAEPs with the factors of aging, high-frequency hearing loss and sensation level of the CAEP test stimulus. Results. Aging was significantly associated with prolonged N1 and P2 latencies and reduced P2 amplitude. Elevated thresholds related to the sensation level of the CAEP stimulus were significantly associated with increased N1 and P2 amplitudes and decreased N1 latency. A significant relationship was detected between high-frequency hearing thresholds and the shortening of P2 latencies and the reduction of P2 amplitudes. Conclusion. The results of this study highlight the complex interplay of aging, high-frequency hearing loss and the sensation level of the CAEP stimulus on CAEP components in elderly people. These factors should be considered in future research using CAEPs to enhance overall understanding of auditory processing in the aging population., Competing Interests: Declaration of Conflicting InterestsThe authors declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Context: Aided Cortical Auditory Evoked Potentials (CAEPs) can be one of the objective methods to assess benefit from hearing devices in difficult-to-test population. There is a dearth of studies using CAEPs to evaluate the benefit obtained with bimodal stimulation. Aim: The aim of the present investigation was to investigate if CAEPs can be used as an objective measure to assess benefit from bimodal stimulation. Participants and Methods: CAEPs using /t/ stimmulus was recorded from 6 children in 3 conditions (using only hearing aid, with only cochlear implant [CI] and using bimodal condition). Behavioral tests carried out included aided sound field thresholds and Early Speech Perception Test (ESP) in auditory mode. Results: CI assisted thresholds for all the six children were within speech spectrum whereas hearing aid assisted thresholds were within speech spectrum for three children and outside speech spectrum for three. The results of ESP complimented the aided thresholds. Amplitude of CAEPs appeared to show an association with behavioural measures. The amplitude of CAEPs were lesser when the benefit from hearing device was lesser. Conclusion: The results of the present study indicate that CAEPs can be used to evaluate benefit/advantage from bimodal stimulation in difficult-to-test population. This case report series provides empirical evidence for use of CAEPs in clinics. Studies on larger population are needed to confirm the results of the present study. [ABSTRACT FROM AUTHOR]

Background: Late latency auditory evoked potentials (LLAEPs) provide objective evidence of an individual's central auditory processing abilities. Electrically evoked cortical auditory evoked potentials (eCAEPs) are a type of LLAEP that provides an objective measure of aided speech perception and auditory processing abilities in cochlear implant (CI) recipients.Aim: To determine the short-term test-retest reliability of eCAEPs in adult CI recipients.Design: An explorative, within-subject repeated measures research design was employed.Study Sample: The study sample included 12 post-lingually deafened, unilaterally implanted adult CI recipients with at least 9 months of CI experience.Method: eCAEPs representing basal, medial and apical cochlear regions were recorded in the implanted ears of each participant. Measurements were repeated 7 days after the initial assessment.Results: No significant differences between either median latencies or amplitudes at test and retest sessions (p > 0.05) were found when results for apical, medial and basal electrodes were averaged together. Mean intraclass correlation coefficient (ICC) scores averaged across basal, medial and apical cochlear stimulus regions indicated that both consistency and agreement were statistically significant and ranged from moderate to good (ICC = 0.58–0.86, p < 0.05). ICC confidence intervals did demonstrate considerable individual variability in both latency and amplitudes.Conclusion: eCAEP latencies and amplitudes demonstrated moderate to good short-term test-retest reliability. However, confidence intervals indicated individual variability in measurement consistency which is likely linked to attention and listening effort required from the CI recipients.

Objective: This study describes a new automated strategy to determine the detection status of an electrophysiological response. Design: Response, noise and signal-to-noise ratio of the cortical auditory evoked potential (CAEP) were characterised. Detection rules were defined: when to start testing, when to conduct subsequent statistical tests using residual noise as an objective criterion, and when to stop testing. Study sample: Simulations were run to determine optimal parameters on a large combined CAEP data set collected in 45 normal-hearing adults and 17 adults with hearing loss. Results: The proposed strategy to detect CAEPs is fully automated. The first statistical test is conducted when the residual noise level is equal to or smaller than 5.1 µV. The succeeding Hotelling's T2 statistical tests are conducted using pre-defined residual noise levels criteria ranging from 5.1 to 1.2 µV. A rule was introduced allowing to stop testing before the maximum number of recorded epochs is reached, depending on a minimum p-value criterion. Conclusion: The proposed framework can be applied to systems which involves detection of electrophysiological responses in biological systems containing background noise. The proposed detection algorithm which optimise sensitivity, specificity, and recording time has the potential to be used in clinical setting. [ABSTRACT FROM AUTHOR]

Background/aim: The aim of this study was to determine the age-related latency interval of P1 latencies of children with normal hearing, and to evaluate the P1 latency changes after surgery in children who underwent cochlear implantation. Materials and methods: We evaluated 60 children with normal hearing and 16 children with cochlear implants aged 0-6 years using cortical auditory evoked potentials. P1 latencies were measured only once in the children with normal hearing, and on the postoperative first day, and the first, third, and sixth postoperative months in the children with cochlear implants. Results: There was a statistically significant decrease in the P1 latencies as the age increased in children with normal hearing (P < 0.001). It was determined that when the external partof the cochlear implant was applied, the P1 latencies of children with cochlear implants were significantly longer than those of age-matched children with normal hearing (P < 0.001). This difference disappeared in 10 children with implants at the third and sixth months, but significant differences remained in 6 children. Conclusion: P1 latency could be used as an objective tool to evaluate the normal development of auditory pathways, and may be helpful in the effective programming of children undergoing cochlear implantation. [ABSTRACT FROM AUTHOR]

Objective: The objective of the study is to establish normative values of cortical evoked response audiometry (CERA) in a heterogeneous Indian population and correlate CERA threshold with pure tone audiometric (PTA) threshold values. Materials and Methods: A prospective study was carried out on 31 volunteers (n = 62) who had no otological or neurological complaints. Two study groups were formed; Group 1 with individuals from 20 to 40 years (mean age of 29.1 years) and Group 2 with individuals from 41 to 60 years (mean age of 46.2 years). The latencies and amplitudes of the waves of P1, N1, and P2 at threshold and 70 dBnHL were measured. Results: Twenty-nine participants (94% of the ears) had CERA threshold within 20 dB of true behavioral threshold with only 6% having a difference of >20 dB with their PTA thresholds. There was a significant difference (P < 0.05) at 70 dB in amplitudes for waves P1, N1, and P2 at 2 kHz and additionally at 1 kHz for N1 between the two groups. Conclusion: Normative values for CERA in a heterogeneous Indian population at 70 dB nHL using tone burst stimulus was found to have an average latency of 46.5, 90.1, and 155.5 ms for P1, N1, and P2, respectively. The average amplitude of P1 at 70 dB nHL was 4.3 μV, N1, was 6.5 μV and P2 was 3.2 μV. Hearing threshold obtained with CERA gave a good indication of the actual behavioral hearing threshold of the normal controls, and the age of an individual had a significant effect on the values obtained during CERA testing with N1 being significantly larger at 1 kHz and 2 kHz in older adults when compared to young adults. [ABSTRACT FROM AUTHOR]

Background: Late latency auditory evoked potentials (LLAEPs) provide objective evidence of an individual's central auditory processing abilities. Electrically evoked cortical auditory evoked potentials (eCAEPs) are a type of LLAEP that provides an objective measure of aided speech perception and auditory processing abilities in cochlear implant (CI) recipients. Aim: To determine the short-term test-retest reliability of eCAEPs in adult CI recipients. Design: An explorative, within-subject repeated measures research design was employed. Study Sample: The study sample included 12 post-lingually deafened, unilaterally implanted adult CI recipients with at least 9 months of CI experience. Method: eCAEPs representing basal, medial and apical cochlear regions were recorded in the implanted ears of each participant. Measurements were repeated 7 days after the initial assessment. Results: No significant differences between either median latencies or amplitudes at test and retest sessions (p > 0.05) were found when results for apical, medial and basal electrodes were averaged together. Mean intraclass correlation coefficient (ICC) scores averaged across basal, medial and apical cochlear stimulus regions indicated that both consistency and agreement were statistically significant and ranged from moderate to good (ICC = 0.58–0.86, p < 0.05). ICC confidence intervals did demonstrate considerable individual variability in both latency and amplitudes. Conclusion: eCAEP latencies and amplitudes demonstrated moderate to good short-term test-retest reliability. However, confidence intervals indicated individual variability in measurement consistency which is likely linked to attention and listening effort required from the CI recipients. [ABSTRACT FROM AUTHOR]

Mild cognitive impairment (MCI) is considered an intermediate transitional stage for the development of dementia, especially Alzheimer's disease. The identification of neurophysiological biomarkers for MCI will allow improvement in detecting and tracking the progression of cognitive impairment. The primary objective of this study was to compare cortical auditory evoked potentials between older adults with and without probable MCI to identify potential neurophysiological indicators of cognitive impairment. We applied a temporal‐spatial principal component analysis to the evoked potentials achieved during the processing of pure tones and speech sounds, to facilitate the separation of the components of the P1‐N1‐P2 complex. The probable MCI group showed a significant amplitude increase in a factor modeling N1b for speech sounds (Cohen's d = .84) and a decrease in a factor around the P2 time interval, especially for pure tones (Cohen's d = 1.17). Moreover, both factors showed a fair discrimination value between groups (area under the curve [AUC] = .698 for N1b in speech condition; AUC = .746 for P2 in tone condition), with high sensitivity to detect MCI cases (86% and 91%, respectively). The results for N1b suggest that MCI participants may suffer from a deficit to inhibit irrelevant speech information, and the decrease of P2 amplitude could be a signal of cholinergic hypoactivation. Therefore, both components could be proposed as early biomarkers of cognitive impairment. Cortical auditory evoked potentials during the processing of pure tones and speech sounds are suitable to detect mild cognitive impairment. The present study uses principal component analysis applied to cortical auditory evoked potentials to obtain neurophysiological biomarkers for mild cognitive impairment. Amplitude increase around N1b for speech sounds and amplitude decrease around P2 for pure tones might be early biomarkers of cognitive impairment. Moreover, N1b and P2 factors amplitude correctly classify around 90% of individuals with mild cognitive impairment. [ABSTRACT FROM AUTHOR]

Individuals with Autism Spectrum Disorder (ASD) experience challenges with social communication, often involving emotional elements of language. This may stem from underlying auditory processing difficulties, especially when incoming speech is nuanced or complex. This study explored the effects of auditory training on social perception abilities of children with ASD. The training combined use of a remote-microphone hearing system and computerized emotion perception training. At baseline, children with ASD had poorer social communication scores and delayed mismatch negativity (MMN) compared to typically developing children. Behavioral results, measured pre- and post-intervention, revealed increased social perception scores in children with ASD to the extent that they outperformed their typically developing peers post-intervention. Electrophysiology results revealed changes in neural responses to emotional speech stimuli. Post-intervention, mismatch responses of children with ASD more closely resembled their neurotypical peers, with shorter MMN latencies, a significantly heightened P2 wave, and greater differentiation of emotional stimuli, consistent with their improved behavioral results. This study sets the foundation for further investigation into connections between auditory processing difficulties and social perception and communication for individuals with ASD, and provides a promising indication that combining amplified hearing and computer-based targeted social perception training using emotional speech stimuli may have neuro-rehabilitative benefits.

The present study aimed to determine the relationship between aided cortical auditory evoked potentials and aided behavioral thresholds. Secondary aims of the study were to investigate the relationship between age and Cortical Auditory Evoked Potentials latencies, and to analyze the relationship between the /m/, /g/ and /t/ stimuli. Therefore, 20 subjects (4-8 years old) who diagnosed with moderate to severe hearing loss were included in the study. Behavioral pure-tone audiometry was performed using supra-aural earphones. After verification of the settings of hearing aid settings, aided behavioral thresholds were determined in the free field. Aided CAEPs were recorded using the HEARLab system in a sound-treated room. The /m/, /g/, and /t/ speech stimuli were applied with durations of 30, 20, and 30 ms respectively. A strong correlation was found between aided cortical auditory evoked responses at the level of 55 dB SPL and aided behavioral thresholds in the free field(r=0.86). We showed that the CAEP latencies were not correlated with the age (/m/ stimulus [r=-0.051; p=0.830], /g/ stimulus [r=-0.053; p=0.825], and /t/ stimulus [r=0.121; p=0,610]). The mean latency of the /m/ stimulus at 55 dB SPL intensity was longer than those of the /g/ and /t/ stimuli. The results of the present study demonstrated that the use of the cortical auditory evoked potentials is clinically useful for measuring the hearing aid benefit. The CAEP can predict the aided behavioral thresholds in children with moderate hearing loss. [ABSTRACT FROM AUTHOR]

Purpose: Cortical auditory evoked potential (CAEP) procedures are a useful way of estimating behavioural thresholds without active participant cooperation. They are becoming more common in hearing aid fitting, especially for those who cannot give reliable responses during evaluation. Speech stimuli are used in CAEP assessment to better understand listener performance when listening to speech. A commercial system, HEARLab (Frye Electronics, Tigard OR), detects and automatically analyses aided CAEPs elicited by speech stimuli. Aided CAEPs are also helpful in cochlear implant evaluation. However, there are few studies in this area, primarily due to electrical artefacts elicited by such devices. This study determined average CAEP waveform latency for CI users, and compared aided HEARLab cortical assessment (ACA) outcomes with behavioural speech detection results, using modified recording electrodes designed to reduce artefacts. Method: Custom CAEP electrodes were used to reduce recording artefacts, and test outcomes compared with those obtained with standard electrodes. Recordings from participants using two types of cochlear implant device (Cochlear and Advanced Bionics) were also compared. Twenty adult cochlear implantees were assessed using ACA with both types of electrodes, and behavioural free field speech detection was also conducted. Results: Average P1 latencies for the cochlear implant users were within the normative range of the general, non-implant population. The percentage of matches for positive results between ACA and behavioural speech detection test results was low, and the number of CAEPs recorded without artefacts was also low for both types of electrodes. More CAEPs could be recorded without artefacts with Cochlear devices regardless of the type of electrodes used. However, the artefact amplitudes recorded with Cochlear devices were greater than those produced by Advanced Bionics devices. Conclusion: Custom electrodes were not effective in reducing the prevalence of CI-related artefacts, and the artefact amplitude recorded was slightly greater than for the original electrodes. Alternative methods should be trialled to reduce the effects of electrical artefacts on CAEP recordings with cochlear implant users. [ABSTRACT FROM AUTHOR]

Auditory neuropathy/spectrum disorder (ANSD), also referred to as auditory neuropathy/dys-synchrony (AN/AD) is a recently described form of hearing impairment. Many studies have shown that changing the pattern of afferent input to the cortex significantly affects cortical organization and there is little studies about cortical neuromaturation and plasticity in children with ANSD. Study of P1 component of cortical auditory evoked potentials (CAEPs) in children with ANSD. This survey was descriptive cross-sectional. During that 97 hearing impairment children were under hearing screening tests. Of these, 14 selected subjects (ear = 28) diagnosed with ANSD (an average age of 8.5 years) and evaluated by P1 component of CAEPs. Based on latency results of p1 wave, the ears of the subjects fell into two seperate groups: Control (normal: n = 10) and case {total: n = 18 (delayed: n = 12) + (absent: n = 6)}. The averages of mean latency of P1 components of the case group in the right and the left ears compared to the control group had significant differences (p < 0.05). Abnormal latency of p1 component in ANSD children shows the possibility of different scales of disturbances in cortical auditory maturation and grow. [ABSTRACT FROM AUTHOR]

Abstract The perceptual separation between a signal speech and a competing speech (masker), induced by the precedence effect, plays an important role in releasing the signal speech from the masker, especially in a reverberant environment. The perceptual-separation-induced unmasking effect has been suggested to involve multiple cognitive processes, such as selective attention. However, whether listeners' spatial attention modulate the perceptual-separation-induced unmasking effect is not clear. The present study investigated how perceptual separation and auditory spatial attention interact with each other to facilitate speech perception under a simulated noisy and reverberant environment by analyzing the cortical auditory evoked potentials to the signal speech. The results showed that the N1 wave was significantly enhanced by perceptual separation between the signal and masker regardless of whether the participants' spatial attention was directed to the signal or not. However, the P2 wave was significantly enhanced by perceptual separation only when the participants attended to the signal speech. The results indicate that the perceptual-separation-induced facilitation of P2 needs more attentional resource than that of N1. The results also showed that the signal speech caused an enhanced N1 in the contralateral hemisphere regardless of whether participants' attention was directed to the signal or not. In contrast, the signal speech caused an enhanced P2 in the contralateral hemisphere only when the participant attended to the signal. The results indicate that the hemispheric distribution of N1 is mainly affected by the perceptual features of the acoustic stimuli, while that of P2 is affected by the listeners' attentional status. Highlights • ERPs to a signal syllable masked by two-talker speech are analyzed. • N1 enhancement induced by perceptual separation is independent of spatial attention. • P2 enhancement induced by perceptual separation is dependent on spatial attention. • The perceptual location of the signal syllable affects the scalp distribution of N1. • Listeners' auditory spatial attention affects the scalp distribution of P2. [ABSTRACT FROM AUTHOR]

Decreased central inhibition, possibly related to hearing loss, may contribute to chronic tinnitus. However, many individuals with normal hearing thresholds report tinnitus, suggesting that the percept in this population may arise from sources other than peripheral deafferentation. One measure of inhibition is sensory gating. Sensory gating involves the suppression of non-novel input, and is measured through cortical auditory evoked potential (CAEP) responses to paired stimuli. In typical gating function, amplitude suppression is observed in the second CAEP response when compared to the first CAEP response, illustrating inhibitory activity. Using this measure, we investigated central inhibitory processes in normal hearing young adults with and without mild tinnitus to determine whether inhibition may be a contributing factor to the tinnitus percept. Results showed that gating function was impaired in the tinnitus group, with the CAEP Pa component significantly correlated with tinnitus severity. Further exploratory analyses were conducted to evaluate variability in gating function within the tinnitus group, and findings showed that high CAEP amplitude suppressors demonstrated gating performance comparable to adults without tinnitus, while low amplitude suppressors exhibited atypical gating function.

Background: Among individuals with vestibular dysfunction, the loss of vestibular sensory information is found to alter cognitive abilities that coordinate spatial and non-spatial information. P300 is an event-related potential commonly used to assess cognitive processing. The aim of the present study was to compare the latency and amplitude of cortical auditory evoked potential and P300 between individuals with vestibular dysfunction and individuals with no vestibular dysfunction. Methods: Forty adults with a mean age of 40.5 ± 13.07 participated in the study. Group I included 20 adults diagnosed with vestibular dysfunction and group II included 20 age-matched adults with no vestibular dysfunction. The P300 was recorded from the electrode site Cz and Pz. It was elicited using pure-tones in odd-ball paradigm. The latency and amplitude of peaks P1, N1, P2, and N2 of the cortical auditory evoked potential and the P300 were measured. Results: Significant amplitude difference was observed in cortical potentials at Cz and Pz. The P300 was present only in 70% of individuals with vestibular dysfunction compared to 100% among individuals with no vestibular dysfunction. The mean amplitude of the P300 was slightly larger in group 1 compared to group 2 and the mean latency of the P300 was similar in both groups. However, the difference in amplitude of the P300 between groups was not statistically significant. Conclusions: Knowing the cognitive function of individuals with vestibular dysfunction enables planning vestibular rehabilitation therapy, which enhances the quality of life in these individuals by improving their vestibular and cognitive functions., Competing Interests: No competing interests were disclosed., (Copyright: © 2023 Kumar K et al.)

Objectives: The objective assessment tests overcome the variability of subjective methods. Cortical recordings with gap pre-pulse inhibition of the acoustic startle reflex stimulus have been used as objective tinnitus assessments in humans. This study aims to investigate this possible objective tinnitus test and compare gap-induced inhibition in different stimulus parameters and brain regions., Materials & Methods: Twenty People (18-50 years old) without hearing loss and tinnitus were included. The sound stimuli consisted of continuous background noise with a loud startle tone preceded by a silent gap (20 and 40 ms duration, 120 and 150 ms distance from the startle). The N1-P2 complex amplitude and topoplot maps were extracted in 27-channel cortical response recording after signal processing. Four brain regions of interest (ROI) of anterior-frontal, centro-frontal, right, and left temporal were investigated., Results: The results showed that the maximum inhibition occurred in a 40 ms gap duration and 150 ms distance in all 4 ROIs. In comparing ROIs, the centro-frontal and left temporal regions revealed the most inhibition (p<0.05). The decrease in the amplitude of the N1 and P2 in that region could also be traced in the 100 and 200 ms topoplots., Conclusion: Gap-induced inhibition was observed in all gap-embedded stimuli and all ROIs. However, the 40-150 mode and centro-frontal and left temporal regions had maximum inhibition in normal subjects. It provides a promising tool for objectively assessing tinnitus in humans with particular implications in children., Competing Interests: The authors have no relevant financial or non-financial interests to disclose., (© 2023 The Authors.)

Abstract Understanding speech in background noise is often more difficult for individuals who are older and have hearing impairment than for younger, normal-hearing individuals. In fact, speech-understanding abilities among older individuals with hearing impairment varies greatly. Researchers have hypothesized that some of that variability can be explained by how the brain encodes speech signals in the presence of noise, and that brain measures may be useful for predicting behavioral performance in difficult-to-test patients. In a series of experiments, we have explored the effects of age and hearing impairment in both brain and behavioral domains with the goal of using brain measures to improve our understanding of speech-in-noise difficulties. The behavioral measures examined showed effect sizes for hearing impairment that were 6–10 dB larger than the effects of age when tested in steady-state noise, whereas electrophysiological age effects were similar in magnitude to those of hearing impairment. Both age and hearing status influence neural responses to speech as well as speech understanding in background noise. These effects can in turn be modulated by other factors, such as the characteristics of the background noise itself. Finally, the use of electrophysiology to predict performance on receptive speech-in-noise tasks holds promise, demonstrating root-mean-square prediction errors as small as 1–2 dB. An important next step in this field of inquiry is to sample the aging and hearing impairment variables continuously (rather than categorically) – across the whole lifespan and audiogram – to improve effect estimates. Highlights • Listening in noise is unavoidable; common real-world SNRs fall between 0 and 15 dB. • Speech understanding in noise (SNR50) varies widely for hearing-impaired individuals. • Age effects on SNR50 range from 2 to 4 dB; hearing impairment effects range from 2 to 12 dB. • Age and hearing-impairment effects on cortical auditory evoked potentials (CAEPs) are complex. • CAEP-based predictions of behavior within 2 dB of measured SNR50s. [ABSTRACT FROM AUTHOR]

Abstract Hearing loss can impair auditory discrimination, especially in noisy environments, requiring greater listening effort, which can impact socio-occupational life. To assess the impact of hearing loss in noisy environments, clinicians may use subjective or objective methods. Subjective methods, such as speech audiometry in noise, are used in clinical practice to assess reported discomfort. Objective methods, such as cortical auditory evoked potentials (CAEPs), are mainly used in research. Subjective methods mainly comprise speech audiometry in noise, in which the signal-to-noise ratio can be varied so as to determine the individual speech recognition threshold, with and without hearing rehabilitation, the aim being to highlight any improvement in auditory performance. Frequency discrimination analysis is also possible. Objective methods assess auditory discrimination without the patient's active participation. One technique used for patients with auditory rehabilitation is the study of auditory responses by CAEPs. This electrophysiological examination studies cortical auditory rehabilitation oddball paradigms, enabling wave recordings such as mismatch negativity, P300 or N400, and analysis of neurophysiological markers according to auditory performance. The present article reviews all these methods, in order to better understand and evaluate the impact of hearing loss in everyday life. [ABSTRACT FROM AUTHOR]

Pelizaeus-Merzbacher disease (PMD; MIM 312080), an inherited defect of central nervous system myelin formation, affects individuals in many ways, including their hearing and language abilities. The aim of this study was to assess the auditory abilities in 18 patients with PMD by examining the functional processes along the central auditory pathways using auditory brainstem responses (ABR) and cortical auditory evoked potentials (CAEP) in response to speech sounds. The significant ABR anomalies confirm the existence of dyssynchrony previously described at the level of the brainstem in patients with PMD. Despite the significant auditory dyssynchrony observed at the level of the brainstem, CAEPs were present in most patients, albeit somehow abnormal in terms of morphology and latency, resembling a type of auditory neuropathy spectrum disorder. [ABSTRACT FROM AUTHOR]

Decreased central inhibition, possibly related to hearing loss, may contribute to chronic tinnitus. However, many individuals with normal hearing thresholds report tinnitus, suggesting that the percept in this population may arise from sources other than peripheral deafferentation. One measure of inhibition is sensory gating. Sensory gating involves the suppression of non-novel input, and is measured through cortical auditory evoked potential (CAEP) responses to paired stimuli. In typical gating function, amplitude suppression is observed in the second CAEP response when compared to the first CAEP response, illustrating inhibitory activity. Using this measure, we investigated central inhibitory processes in normal hearing young adults with and without mild tinnitus to determine whether inhibition may be a contributing factor to the tinnitus percept. Results showed that gating function was impaired in the tinnitus group, with the CAEP Pa component sig-nificantly correlated with tinnitus severity. Further exploratory analyses were conducted to evaluate variability in gating function within the tinnitus group, and findings showed that high CAEP amplitude suppressors demonstrated gating performance comparable to adults without tinnitus, while low amplitude suppressors exhibited atypical gating function. [ABSTRACT FROM AUTHOR]

Objective: The current research investigated whether professional musicians outperformed non-musicians on auditory processing and speech-in-noise perception as assessed using behavioural and electrophysiological tasks.Design: Spectro-temporal processing skills were assessed using a psychoacoustic test battery. Speech-in-noise perception was measured using the Listening in Spatialised Noise – Sentences (LiSN-S) test and Cortical Auditory Evoked Potentials (CAEPs) recorded to the speech syllable/da/presented in quiet and in 8-talker babble noise at 0, 5, and 10 dB signal-to-noise ratios (SNRs).Study sample: Ten professional musicians and 10 non-musicians participated in this study.Results: Musicians significantly outperformed non-musicians in the frequency discrimination task and low-cue condition of the LiSN-S test. Musicians’ N1 amplitude showed no difference between 5 dB and 0 dB SNR conditions while non-musicians showed significantly lower N1 amplitude at 0 dB SNR compared to 5 dB SNR. Brain-behaviour correlation for musicians showed a significant association between CAEPs at 5 dB SNR and the low-cue condition of the LiSN-S test at 30–70 ms. Time–frequency analysis indicated musicians had significantly higher alpha power desynchronisation in the 0 dB SNR condition indicating involvement of attention.Conclusions: Through the use of behavioural and electrophysiological data, the results provide converging evidence for improved speech recognition in noise in musicians. [ABSTRACT FROM AUTHOR]

Cortical auditory evoked potentials represent summation of neural activity in the auditory pathways in response to sounds. They provide an objective measure of the brain’s response to sound. For this reason, they are an effective tool for scientists and audiologists for investigating auditory function in normal people and those with hearing loss. The main objective of this study is to determine what components among the P1, N1, P2, N2, or P3 are most beneficial in assessing the speech detection and discrimination abilities of adult sensorineural hearing loss population. This study also intends to investigate whether changes in the amplitudes and latencies of these components occurring with sensorineural hearing loss and hearing aids differ in responses reflecting different stages of auditory processing. Auditory Potentials were recorded to /ba/ and /da/ stimuli from two Malay adult groups. A control group of 12 right-handed having normal hearing and a group of 10 right-handed with sensorineural hearing loss. The results showed that P2 and P3 components had the most benefits from the use of hearing aids in the hearing loss subjects and therefore could be used in both clinical and research applications as a predictor and objective indicator of hearing aids performance in speech perception. The study also showed that the brain processes both stimuli in a different pattern for both the normal and the aided hearing loss subjects. The present study could provide more diagnostic information for clinicians and could also offer better speech perception benefits for hearing-impaired individuals from their personal hearing aids. The findings also suggest that the aided hearing loss subjects, despite the benefits they get from the hearing aids, find it difficult to detect and discriminate the acoustic differences between the two speech stimuli. [ABSTRACT FROM AUTHOR]

The effects of background noise on speech-evoked cortical auditory evoked potentials ( CAEPs) can provide insight into the physiology of the auditory system. The purpose of this study was to determine background noise effects on neural coding of different phonemes within a syllable. CAEPs were recorded from 15 young normal-hearing adults in response to speech signals /s/, /ɑ/, and /sɑ/. Signals were presented at varying signal-to-noise ratios ( SNRs). The effects of SNR and context (in isolation or within syllable) were analyzed for both phonemes. For all three stimuli, latencies generally decreased and amplitudes generally increased as SNR improved, and context effects were not present; however, the amplitude of the /ɑ/ response was the exception, showing no SNR effect and a significant context effect. Differential coding of /s/ and /ɑ/ likely result from level and timing differences. Neural refractoriness may result in the lack of a robust SNR effect on amplitude in the syllable context. The stable amplitude across SNRs in response to the vowel in /sɑ/ suggests the combined effects of (1) acoustic characteristics of the syllable and noise at poor SNRs and (2) refractory effects resulting from phoneme timing at good SNRs. Results provide insights into the coding of multiple-onset speech syllables in varying levels of background noise and, together with behavioral measures, may help to improve our understanding of speech-perception-in-noise difficulties. [ABSTRACT FROM AUTHOR]