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Child listeners have particular difficulty with speech perception when competing speech noise is present; this challenge is often attributed to their immature top-down processing abilities. The purpose of this study was to determine if the effects of competing speech noise on speech-sound processing vary with age. Cortical auditory evoked potentials (CAEPs) were measured during an active speech-syllable discrimination task in 58 normal-hearing participants (age 7–25 years). Speech syllables were presented in quiet and embedded in competing speech noise (4-talker babble, +15 dB signal-to-noise ratio; SNR). While noise was expected to similarly reduce amplitude and delay latencies of N1 and P2 peaks in all listeners, it was hypothesized that effects of noise on the P3b peak would be inversely related to age due to the maturation of top-down processing abilities throughout childhood. Consistent with previous work, results showed that a +15 dB SNR reduces amplitudes and delays latencies of CAEPs for listeners of all ages, affecting speech-sound processing, delaying stimulus evaluation, and causing a reduction in behavioral speech-sound discrimination. Contrary to expectations, findings suggest that competing speech noise at a +15 dB SNR may have similar effects on various stages of speech-sound processing for listeners of all ages. Future research directions should examine how more difficult listening conditions (poorer SNRs) might affect results across ages.

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.

Objectives This study aimed to objectively evaluate access to soft sounds (55 dB SPL) in paediatric CI users, all wearing MED-EL (Innsbruck, Austria) devices who were fitted with the objective electrically elicited stapedius reflex threshold (eSRT) fitting method, to track their cortical auditory evoked potential (CAEP) presence and latency, and to compare their CAEPs to those of normal-hearing peers. Methods Forty-five unilaterally implanted, pre-lingually deafened MED-EL CI users, aged 12–48 months, underwent CAEP testing in the clinic at regular monthly intervals post switch-on. CAEPs were recorded in response to short speech tokens /m/, /g/ and /t/ presented in the free field at 55 dB SPL. Twenty children with normal hearing (NH), similarly aged, underwent CAEP testing once. Results The proportion of present CAEPs increased and CAEP P1 latencies reduced significantly with post-implantation duration. CAEPs were scored based on their presence and age-appropriate P1 latency. These CAEP scores increased significantly with post-implantation duration. CAEP scores were significantly worse for the /m/ speech token compared to the other two tokens. Compared to the NH group, CAEP scores were significantly smaller for all post-implantation test intervals. Conclusions This study provides clinicians with a first step towards typical ranges of CAEP presence, latency, and derived CAEP score over the first months of MED-EL CI use. CAEPs within these typical ranges could validate intervention whereas less than optimum CAEPs could prompt clinicians to seek solutions in a timely manner. CAEPs could clinically validate whether a CI provides adequate access to soft sounds. This approach could form an alternative to behavioural soft sound access verification.

As a result of newborn hearing screening, hearing aids are usually prescribed and fitted by 2-3 months of age. However, the assessment data used for prescribing hearing aids in infants and toddlers are limited in quality and quantity. There is great interest in finding appropriate physiological measures that can be help to facilitate and improve the management process of hearing impaired children. It seems that cortical auditory evoked potentials (CAEPs) can provide information before it is possible to obtain reliable information from behavioral assessment procedures. This article will review the studies conducted in this area during the past15 years to determine the advantages, disadvantages and future research areas of CAEPs as an objective method in the management of hearing impaired children.

Cochlear implants (CIs) can be used effectively in the profoundly impaired children individuals. Objectives This work was designed to assess speech processing at brainstem and cortical level in children fitted with CIs to investigate the possible influence of brainstem processing of speech on the cortical processing in those children. Method Twenty children fitted with CIs underwent aided sound-field audiologic evaluation, speech evoked cortical auditory evoked potentials (S-CAEPs) and according to the results, children were classified into two groups: group I with good cortical response and group II with poor cortical response. This was followed by speech evoked ABR (S-ABR) recoding. Results P1 component of CAEPs was recorded in all children while other component showed variable results. S-ABR was recorded in all children even those with poor S-CAEPs response who showed delayed D, E, F and O latencies. However, S-ABR amplitudes did not show any significant difference between both groups. Conclusions Children fitted with CI showed immediate cortical activation following device programming and this activity depends on the age of implantation as well as the child's age. S-ABR provides a new clinical tool that showed an important role of brainstem in complex sound processing that contribute to cortical processing.

Studies about cortical auditory evoked potentials using the speech stimuli in normal hearing individuals are important for understanding how the complexity of the stimulus influences the characteristics of the cortical potential generated.ObjectiveTo characterize the cortical auditory evoked potential and the P3 auditory cognitive potential with the vocalic and consonantal contrast stimuli in normally hearing individuals.Method31 individuals with no risk for hearing, neurologic and language alterations, in the age range between 7 and 30 years, participated in this study. The cortical auditory evoked potentials and the P3 auditory cognitive one were recorded in the Fz and Cz active channels using consonantal (/ba/-/da/) and vocalic (/i/-/a/) speech contrasts. Design: A cross-sectional prospective cohort study.ResultsWe found a statistically significant difference between the speech contrast used and the latencies of the N2 (p = 0.00) and P3 (p = 0.00) components, as well as between the active channel considered (Fz/Cz) and the P3 latency and amplitude values. These correlations did not occur for the exogenous components N1 and P2.ConclusionThe speech stimulus contrast, vocalic or consonantal, must be taken into account in the analysis of the cortical auditory evoked potential, N2 component, and auditory cognitive P3 potential.

Objectives In congenitally deaf children fit with a cochlear implant, little is known about the maturation of the auditory cortex. Cortical auditory evoked potentials are a useful methodology to study the auditory cortical system of children with cochlear implants. Nevertheless, these recordings are contaminated by a cochlear implant artifact. The objective of this study was to use independent component analysis to minimize the artifact of the cochlear implant to study cortical auditory evoked potentials. Study design Prospective study. Method A total of 5 children ranging in age from 21 to 49 months who were fitted with a cochlear implant for at least 6 months were included in this study. The stimuli were pure tones (750 Hz, 200 ms duration, 70 dB SPL) presented with an irregular interstimulus interval (1000–2000 ms) via loud speakers. The cortical auditory evoked potentials were recorded from 17 Ag–AgCl electrodes referenced to the nose. The peak latency and amplitude of each deflection culminating at the fronto-central and temporal sites were analyzed. Main outcome measures The P100–N250 peak latencies and amplitudes of the cortical auditory evoked potentials recorded from children fitted with cochlear implants. Scalp map potentials distributions were done for each child for the N250 wave. Results The use of independent component analysis permitted to minimize the cochlear implant artifact for the five children. Cortical auditory evoked potentials were recorded at fronto-central and temporal sites. Scalp map potentials distributions for the N2 wave showed activation of temporal generators contralateral at the CI for the five children. Conclusion This preliminary electrophysiological study confirms the value and the limits of independent component analysis. It could allow longitudinal studies in cochlear implant users to examine the maturation of auditory cortex. It could also be used to identify objective cortical electrophysiological measures to help the fitting of CIs in children.

Behavioral perceptions and cortical auditory evoked potentials (CAEPs) from native English (N=10) and Spanish speakers (N=10) were recorded for speech stimuli that constitute phonetically relevant categories of voicing. The stimuli were synthesized bilabial stop consonant-vowel syllables in a continuum ranging from/ba/to/pa/that varied in voice onset time (VOT) from 0 to 60 ms. Different behavioral perceptions were evidenced by significantly different categorical phonetic boundaries between the two groups (p.0001). In contrast, there were no significant differences in CAEP component P1, N1, and P2 mean latencies or P1-N1 and N1-P2 amplitudes between groups (p.05). Peak P1, N1, and P2 response latencies and P1-N1 and N1-P2 amplitudes increased significantly with increasing VOTs (p.0001 and p.001, respectively). There were no systematic changes in CAEP morphology that corresponded to listeners' perceptual categorical boundaries. These findings are consistent with the notion that changes in morphology of the P1-N1-P2 response are related to acoustical changes in speech sounds and are independent of phonetic categorization of voicing cues across language groups.

To compare two methods of minimizing cochlear implant artifact in cortical auditory evoked potential (CAEP) recordings.Two experiments were conducted. In the first, we assessed the use of independent component analysis (ICA) as a pre-processing filter. In the second, we explored the use of an optimized differential reference (ODR) for minimizing artifacts.Both ICA and the ODR can minimize the artifact and allow measurement of CAEP responses.When using a large number of recording electrodes ICA can be used to minimize the implant artifact. When using a single electrode montage an optimized differential reference is adequate to minimize the artifact.The use of an optimized differential reference could allow cortical evoked potentials to be used in routine clinical assessment of auditory pathway development in children and adults fit with cochlear implants.

One child in 750 is born with a handicapping hearing impairment. The methods available to screen and evaluate infants at risk (auditory brainstem responses, middle latency responses, and cortical auditory evoked potentials) are reviewed, explained, and illustrated with case histories.

Bronchopulmonary dysplasia, the most frequent respiratory sequelae of prematurity, usually occurs as part of the multiorgan foetal inflammatory response syndrome. The underlying mechanism is thought to be the same cytokine mediated leukemoid reaction associated with periventricular leukomalacia of premature infants. Event-related potentials have been shown to serve as early indicators of problems in cortical development. Our aim was to determine the effect of bronchopulmonary dysplasia on neonatal cortical auditory processing. Forty-five premature infants (23–34 weeks) were recorded at 35 post-conceptional weeks. Infants with genetic syndromes, clinical evidence of neonatal encephalopathy, intra-ventricular haemorrhage or periventricular leukomalacia were not recruited. The average of 330 responses to 1000 Hz pure tones (inter-stimulus interval 1250–1850 ms), were recorded at frontal location. Mean amplitudes calculated from the data points of 30 ms centered on P1 and N2 peaks in the waveforms of each subject were measured. The amplitude of P1 component resulted lower in infants with bronchopulmonary dysplasia (p = .004). Results show an association between bronchopulmonary dysplasia and alterations in brain auditory processing, even in absence of major neurological risk factors. This further support the hypothesis of an interference with brain development mediated by the foetal inflammatory response syndrome.

Anesthetizing or sedating animals affords control over movement artifact during electrophysiological recording. However, the use of chemical restraint leads to unwanted side effects such as drug-induced hypothermia. Hypothermia is problematic because BAEP amplitudes and latencies are affected significantly by core temperature changes. Moreover, several recent studies have indicated that anesthetics and sedatives may significantly alter the BAEP and CAEP even in thermoregulated subjects. There is a need, therefore, to develop a practical technique for obtaining chronic BAEPs and CAEPs in restrained, unanesthetized animals. The present report describes a technique that permits the gathering of consistent, reliable evoked potential recordings over time in unanesthetized mice. The preparation is useful for studying the CNS effects of pharmacological agents, pathological conditions, aging and development in the mouse and could be adapted for use with other small animals as well.

Food deprived cats trained to press a lever on a variable interval schedule for milk reward displayed bursts of relatively large amplitude spindle ECoG activity topographically restricted to the parieto-occipital region during the consumption of reward. An attempt was made to explore the mechanisms involved in these ECoG phenomena known as post-reinforcement synchronization (PRS). When each lever press was rewarded, the parieto-occipital cortex displayed almost continuous spindle bursts whereas the somato-sensory cortex remained desyncronized. In trained subjects both milk or water produced identical PRS. However, when water was substituted for milk during the course of an experiment, PRS was completely suppressed and overt signs of emotionality appeared. Subjects allowed to drink milk from a bowl displayed a similar topographically restricted ECoG synchronization. Both types of consummatory ECoG synchronization were suppressed in darkness or by novel environmental stimuli, and both were indiscernible from sleep-spindle ECoG activity recorded from the same region in satiated subjects, although during sleep the occurrence of spindles did not depend on the presence of light and their cortical distribution was more diffuse. Subjects were habituated to a tone (850 c/sec) or click which did not disrupt their performance and the occurrence of PRS or sleep. The primary and secondary evoked potentials recorded from various cortical projections during bursts of PRS were conspicuously augmented. Their amplitude, much greater than that recorded during relaxed wakefulness in satiated subjects, was comparable to that observed during spindle-slow wave sleep. The evoked potentials recorded after non-rewarded lever pressing; i.e. , during desynchronized ECoG activity were poorly developed; they were comparable to those observed during emotional excitement. Considering the similarity of PRS patterns and sleep ECoG synchronization and assuming that the amplitude of auditory evoked potentials produced by an irrelevant stimulus reflects the fluctuations in the tonus of the reticular activating system (RAS), our results suggest that: (1) PRS is triggered by a transient depression of RAS; and (2) there is a functional overlap between reward centers and hypnogenic ( i.e. , synchronizing) influences.