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Growing evidence shows that partial auditory deprivation leads to extensive neural functional plasticity, which occurs not only in the auditory cortex but also in other sensory regions and cognitive areas. However, studies in structural topological properties are still limited, especially those investigating the relationship between structural connectome alterations and auditory abilities. To clarify this, we investigated white matter structural connectivity changes and the relationship between connection strength and hearing abilities in individuals with long-term single-sided deafness (SSD), a common form of partial hearing deprivation, using diffusion tensor imaging and network-based analysis. The results showed globally improved connection efficiency, locally weakened visual networks, and strengthened fronto-parietal sub-networks in SSD compared to normal hearing controls. Furthermore, a strong positive correlation between hearing abilities (including speech recognition in noise and sound localization) and connection strength, mainly in the fronto-parietal areas, was found in SSD. Our study reveals alteration of the structural network connections in SSD, especially in cognitive related networks, which showed close correlation with hearing abilities. Our findings provide new insights into topological white matter reorganization of the brain after partial sensory deprivation.

We examined the frequency specificity of amplitude envelope patterns in 4 frequency bands, which universally appeared through factor analyses applied to power fluctuations of critical-band filtered speech sounds in 8 different languages/dialects [Ueda and Nakajima (2017). Sci. Rep., 7 (42468)]. A series of 3 perceptual experiments with noise-vocoded speech of Japanese sentences was conducted. Nearly perfect (92–94%) mora recognition was achieved, without any extensive training, in a control condition in which 4-band noise-vocoded speech was employed (Experiments 1–3). Blending amplitude envelope patterns of the frequency bands, which resulted in reducing the number of amplitude envelope patterns while keeping the average spectral levels unchanged, revealed a clear deteriorating effect on intelligibility (Experiment 1). Exchanging amplitude envelope patterns brought generally detrimental effects on intelligibility, especially when involving the 2 lowest bands ( ≲ 1850 Hz; Experiment 2). Exchanging spectral levels averaged in time had a small but significant deteriorating effect on intelligibility in a few conditions (Experiment 3). Frequency specificity in low-frequency-band envelope patterns thus turned out to be conspicuous in speech perception.

Background Pitch perception of complex tones relies on place or temporal fine structure-based mechanisms from resolved harmonics and the temporal envelope of unresolved harmonics. Combining this information is essential for speech-in-noise performance, as it allows segregation of a target speaker from background noise. In hybrid cochlear implant (H-CI) users, low frequency acoustic hearing should provide pitch from resolved harmonics while high frequency electric hearing should provide temporal envelope pitch from unresolved harmonics. How the acoustic and electric auditory inputs interact for H-CI users is largely unknown. Harmonicity and inharmonicity are emergent features of sound in which overtones are concordant or discordant with the fundamental frequency. We hypothesized that some H-CI users would be able to integrate acoustic and electric information for complex tone pitch perception, and that this ability would be correlated with speech-in-noise performance. In this study, we used perception of inharmonicity to demonstrate this integration. Methods Fifteen H-CI users with only acoustic hearing below 500 Hz, only electric hearing above 2 kHz, and more than 6 months CI experience, along with eighteen normal hearing (NH) controls, were presented with harmonic and inharmonic sounds. The stimulus was created with a low frequency component, corresponding with the H-CI user's acoustic hearing (fundamental frequency between 125 and 174 Hz), and a high frequency component, corresponding with electric hearing. Subjects were asked to identify the more inharmonic sound, which requires the perceptual integration of the low and high components. Speech-in-noise performance was tested in both groups using the California Consonant Test (CCT), and perception of Consonant-Nucleus-Consonant (CNC) words in quiet and AzBio sentences in noise were tested for the H-CI users. Results Eight of the H-CI subjects (53%), and all of the NH subjects, scored significantly above chance level for at least one subset of the inharmonicity detection task. Inharmonicity detection ability, but not age or pure tone average, predicted speech scores in a linear model. These results were significantly correlated with speech scores in both quiet and noise for H-CI users, but not with speech in noise performance for NH listeners. Musical experience predicted inharmonicity detection ability, but did not predict speech performance. Conclusions We demonstrate integration of acoustic and electric information in H-CI users for complex pitch sensation. The correlation with speech scores in H-CI users might be associated with the ability to segregate a target speaker from background noise using the speaker's fundamental frequency.

Segregating and understanding speech in complex environments is a major challenge for hearing-impaired (HI) listeners. It remains unclear to what extent these difficulties are dominated by direct interference, such as simultaneous masking, or by a failure of the mechanisms of stream segregation. This study compared HI listeners’ performance with that of young and age-matched normal-hearing (NH) listeners in stream segregation tasks involving speech sounds. Listeners were presented with sequences of speech tokens, each consisting of a fricative consonant and a voiced vowel (CV). The CV tokens were concatenated into interleaved sequences that alternated in fundamental frequency (F0) and/or simulated vocal tract length (VTL). Each pair of interleaved sequences was preceded by a “word” consisting of two random tokens. The listeners were asked to indicate whether the word was present in the following interleaved sequences. The word, if present, occurred within one of the interleaved sequences, so that performance improved if the listeners were able to perceptually segregate the two sequences. Although HI listeners’ identification of the speech tokens in isolation was poorer than that of the NH listeners, HI listeners with both mild and moderate hearing loss were generally able to use both F0 and VTL cues to segregate the interleaved sequences. The results suggest that the difficulties experienced by HI listeners in complex acoustic environments cannot be explained by a loss of basic stream segregation abilities.

In rodents, noise exposure can destroy synapses between inner hair cells and auditory nerve fibers (“cochlear synaptopathy”) without causing hair cell loss. Noise-induced cochlear synaptopathy usually leaves cochlear thresholds unaltered, but is associated with long-term reductions in auditory brainstem response (ABR) amplitudes at medium-to-high sound levels. This pathophysiology has been suggested to degrade speech perception in noise (SPiN), perhaps explaining why SPiN ability varies so widely among audiometrically normal humans. The present study is the first to test for evidence of cochlear synaptopathy in humans with significant SPiN impairment. Individuals were recruited on the basis of self-reported SPiN difficulties and normal pure tone audiometric thresholds. Performance on a listening task identified a subset with “verified” SPiN impairment. This group was matched with controls on the basis of age, sex, and audiometric thresholds up to 14 kHz. ABRs and envelope-following responses (EFRs) were recorded at high stimulus levels, yielding both raw amplitude measures and within-subject difference measures. Past exposure to high sound levels was assessed by detailed structured interview. Impaired SPiN was not associated with greater lifetime noise exposure, nor with any electrophysiological measure. It is conceivable that retrospective self-report cannot reliably capture noise exposure, and that ABRs and EFRs offer limited sensitivity to synaptopathy in humans. Nevertheless, the results do not support the notion that noise-induced synaptopathy is a significant etiology of SPiN impairment with normal audiometric thresholds. It may be that synaptopathy alone does not have significant perceptual consequences, or is not widespread in humans with normal audiograms., Highlights • Study of adults with impaired speech perception in noise (SPiN) and normal audiograms. • A subset of those with reported SPiN impairment exhibited measurable SPiN deficits. • SPiN-impaired participants were matched with controls for age, sex, and audiogram. • Impaired SPiN was not associated with ABR or EFR measures of cochlear synaptopathy. • Impaired SPiN was not associated with a detailed measure of lifetime noise exposure.

Using a well-established binaural-listening paradigm the ability to intentionally switch auditory selective attention was examined under anechoic, low reverberation (0.8 s) and high reverberation (1.75 s) conditions. Twenty-three young, normal-hearing subjects were tested in a within-subject design to analyze influences of the reverberation times. Spoken word pairs by two speakers were presented simultaneously to subjects from two of eight azimuth positions. The stimuli consisted of a single number word, (i.e., 1 to 9), followed by either the direction “UP” or “DOWN” in German. Guided by a visual cue prior to auditory stimulus onset indicating the position of the target speaker, subjects were asked to identify whether the target number was numerically smaller or greater than five and to categorize the direction of the second word. Switch costs, (i.e. reaction time differences between a position switch of the target relative to a position repetition), were larger under the high reverberation condition. Furthermore, the error rates were highly dependent on reverberant energy and reverberation interacted with the congruence effect, (i.e. stimuli spoken by target and distractor may evoke the same answer (congruent) or different answers (incongruent)), indicating larger congruence effects under higher reverberation times.

Recent animal research has shown that exposure to single episodes of intense noise causes cochlear synaptopathy without affecting hearing thresholds. It has been suggested that the same may occur in humans. If so, it is hypothesized that this would result in impaired encoding of sound and lead to difficulties hearing at suprathreshold levels, particularly in challenging listening environments. The primary aim of this study was to investigate the effect of noise exposure on auditory processing, including the perception of speech in noise, in adult humans. A secondary aim was to explore whether musical training might improve some aspects of auditory processing and thus counteract or ameliorate any negative impacts of noise exposure. In a sample of 122 participants (63 female) aged 30–57 years with normal or near-normal hearing thresholds, we conducted audiometric tests, including tympanometry, audiometry, acoustic reflexes, otoacoustic emissions and medial olivocochlear responses. We also assessed temporal and spectral processing, by determining thresholds for detection of amplitude modulation and temporal fine structure. We assessed speech-in-noise perception, and conducted tests of attention, memory and sentence closure. We also calculated participants' accumulated lifetime noise exposure and administered questionnaires to assess self-reported listening difficulty and musical training. The results showed no clear link between participants' lifetime noise exposure and performance on any of the auditory processing or speech-in-noise tasks. Musical training was associated with better performance on the auditory processing tasks, but not the on the speech-in-noise perception tasks. The results indicate that sentence closure skills, working memory, attention, extended high frequency hearing thresholds and medial olivocochlear suppression strength are important factors that are related to the ability to process speech in noise.

The purpose of this study was to establish whether functional near-infrared spectroscopy (fNIRS), an emerging brain-imaging technique based on optical principles, is suitable for studying the brain activity that underlies effortful listening. In an event-related fNIRS experiment, normally-hearing adults listened to sentences that were either clear or degraded (noise vocoded). These sentences were presented simultaneously with a non-speech distractor, and on each trial participants were instructed to attend either to the speech or to the distractor. The primary region of interest for the fNIRS measurements was the left inferior frontal gyrus (LIFG), a cortical region involved in higher-order language processing. The fNIRS results confirmed findings previously reported in the functional magnetic resonance imaging (fMRI) literature. Firstly, the LIFG exhibited an elevated response to degraded versus clear speech, but only when attention was directed towards the speech. This attention-dependent increase in frontal brain activation may be a neural marker for effortful listening. Secondly, during attentive listening to degraded speech, the haemodynamic response peaked significantly later in the LIFG than in superior temporal cortex, possibly reflecting the engagement of working memory to help reconstruct the meaning of degraded sentences. The homologous region in the right hemisphere may play an equivalent role to the LIFG in some left-handed individuals. In conclusion, fNIRS holds promise as a flexible tool to examine the neural signature of effortful listening.

Previous research has reported effects of masker type and signal-to-noise ratio (SNR) on listening effort, as indicated by the peak pupil dilation (PPD) relative to baseline during speech recognition. At about 50% correct sentence recognition performance, increasing SNRs generally results in declining PPDs, indicating reduced effort. However, the decline in PPD over SNRs has been observed to be less pronounced for hearing-impaired (HI) compared to normal-hearing (NH) listeners. The presence of a competing talker during speech recognition generally resulted in larger PPDs as compared to the presence of a fluctuating or stationary background noise. The aim of the present study was to examine the interplay between hearing-status, a broad range of SNRs corresponding to sentence recognition performance varying from 0 to 100% correct, and different masker types (stationary noise and single-talker masker) on the PPD during speech perception. Twenty-five HI and 32 age-matched NH participants listened to sentences across a broad range of SNRs, masked with speech from a single talker (-25 dB to +15 dB SNR) or with stationary noise (-12 dB to +16 dB). Correct sentence recognition scores and pupil responses were recorded during stimulus presentation. With a stationary masker, NH listeners show maximum PPD across a relatively narrow range of low SNRs, while HI listeners show relatively large PPD across a wide range of ecological SNRs. With the single-talker masker, maximum PPD was observed in the mid-range of SNRs around 50% correct sentence recognition performance, while smaller PPDs were observed at lower and higher SNRs. Mixed-model ANOVAs revealed significant interactions between hearing-status and SNR on the PPD for both masker types. Our data show a different pattern of PPDs across SNRs between groups, which indicates that listening and the allocation of effort during listening in daily life environments may be different for NH and HI listeners. (C) 2017 The Authors. Published by Elsevier B.V. Funding Agencies|European Commission [FP7-LISTEN607373]

Restoring normal hearing requires knowledge of how peripheral and central auditory processes are affected by hearing loss. Previous research has focussed primarily on peripheral changes following sensorineural hearing loss, whereas consequences for central auditory processing have received less attention. We examined the ability of hearing-impaired children to direct auditory attention to a voice of interest (based on the talker's spatial location or gender) in the presence of a common form of background noise: the voices of competing talkers (i.e. during multi-talker, or "Cocktail Party" listening). We measured brain activity using electro-encephalography (EEG) when children prepared to direct attention to the spatial location or gender of an upcoming target talker who spoke in a mixture of three talkers. Compared to normally-hearing children, hearing-impaired children showed significantly less evidence of preparatory brain activity when required to direct spatial attention. This finding is consistent with the idea that hearing-impaired children have a reduced ability to prepare spatial attention for an upcoming talker. Moreover, preparatory brain activity was not restored when hearing-impaired children listened with their acoustic hearing aids. An implication of these findings is that steps to improve auditory attention alongside acoustic hearing aids may be required to improve the ability of hearing-impaired children to understand speech in the presence of competing talkers.

Speech communication often takes place in noisy environments; this is an urgent issue for military personnel who must communicate in high-noise environments. The effects of noise on speech recognition vary significantly according to the sources of noise, the number and types of talkers, and the listener's hearing ability. In this review, speech communication is first described as it relates to current standards of hearing assessment for military and civilian populations. The next section categorizes types of noise (also called maskers) according to their temporal characteristics (steady or fluctuating) and perceptive effects (energetic or informational masking). Next, speech recognition difficulties experienced by listeners with hearing loss and by older listeners are summarized, and questions on the possible causes of speech-in-noise difficulty are discussed, including recent suggestions of "hidden hearing loss". The final section describes tests used by military and civilian researchers, audiologists, and hearing technicians to assess performance of an individual in recognizing speech in background noise, as well as metrics that predict performance based on a listener and background noise profile. This article provides readers with an overview of the challenges associated with speech communication in noisy backgrounds, as well as its assessment and potential impact on functional performance, and provides guidance for important new research directions relevant not only to military personnel, but also to employees who work in high noise environments.

The speech-evoked auditory brainstem response (sABR) provides a measure of encoding complex stimuli in the brainstem, and this study employed the sABR to better understand the role of neural temporal jitter in the response patterns from older adults. In experiment 1, sABR recordings were used to investigate age-related differences in periodicity encoding of the temporal envelope and fine structure components of the response to a /da/speech token. A group of younger and a group of older adults (n = 22 per group) participated. The results demonstrated reduced amplitude of the fundamental frequency and harmonic components in the spectral domain of the recorded response of the older listeners. In experiment 2, a model of neural temporal jitter was employed to simulate in a group of young adults (n = 22) the response patterns measured from older adults. A small group of older adults (n = 7) were also tested under the jitter simulation conditions. In the young adults, the results showed a systematic reduction in the response amplitude of the most robust response components as the degree of applied jitter increased. In contrast, the older adults did not demonstrate significant response reduction when tested under jitter conditions. The overall pattern of results suggests that older adults have reduced neural synchrony for encoding periodic, complex signals at the level of the brainstem, and that this reduced synchrony can be modeled by simulating neural jitter via disruption of the temporal waveform of the stimulus.

Although there are numerous papers describing single-channel noise reduction strategies to improve speech perception in a noisy environment, few studies have comprehensively evaluated the effects of noise reduction algorithms on speech quality for hearing impaired (HI). A model-based sparse coding shrinkage (SCS) algorithm has been developed, and has shown previously (Sang et al., 2014) that it is as competitive as a state-of-the-art Wiener filter approach in speech intelligibility. Here, the analysis is extended to include subjective quality ratings and a method called Interpolated Paired Comparison Rating (IPCR) is adopted to quantitatively link the benefit of speech intelligibility and speech quality.The subjective quality tests are performed through IPCR to efficiently quantify noise reduction effects on speech quality. Objective measures including frequency-weighted segmental signal-to-noise ratio (fwsegSNR), perceptual evaluation of speech quality (PESQ) and hearing aid speech quality index (HASQI) are adopted to predict the noise reduction effects.Results show little difference in speech quality between the SCS and the Wiener filter algorithm but a difference in quality rating between the HI and NH listeners. HI listeners generally gave better quality ratings of noise reduction algorithms than NH listeners. However, SCS reduced the noise more efficiently at the cost of higher distortions that were detected by NH but not by the HI.SCS is a promising candidate for noise reduction algorithms for HI. In general, care needs to be taken when adopting algorithms that were originally developed for NH participants into hearing aid applications. An algorithm that is evaluated negatively with NH might still bring benefits for HI participants

What is the best way to help humans adapt to a distorted sensory input? Interest in this question is more than academic. The answer may help facilitate auditory learning by people who became deaf after learning language and later received a cochlear implant (a neural prosthesis that restores hearing through direct electrical stimulation of the auditory nerve). There is evidence that some cochlear implants (which provide information that is spectrally degraded to begin with) stimulate neurons with higher characteristic frequency than the acoustic frequency of the original stimulus. In other words, the stimulus is shifted in frequency with respect to what the listener expects to hear. This frequency misalignment may have a negative influence on speech perception by CI users. However, a perfect frequency-place alignment may result in the loss of important low frequency speech information. A trade-off may involve a gradual approach: start with correct frequency-place alignment to allow listeners to adapt to the spectrally degraded signal first, and then gradually increase the frequency shift to allow them to adapt to it over time. We used an acoustic model of a cochlear implant to measure adaptation to a frequency-shifted signal, using either the gradual approach or the “standard” approach (sudden imposition of the frequency shift). Listeners in both groups showed substantial auditory learning, as measured by increases in speech perception scores over the course of fifteen one-hour training sessions. However, the learning process was faster for listeners who were exposed to the gradual approach. These results suggest that gradual rather than sudden exposure may facilitate perceptual learning in the face of a spectrally degraded, frequency-shifted input. This article is part of a Special Issue entitled .

Early multi-channel designs in the history of cochlear implant development were based on a vocoder-type processing of frequency channels and presented bands of compressed analog stimulus waveforms simultaneously on multiple tonotopically arranged electrodes. The realization that the direct summation of electrical fields as a result of simultaneous electrode stimulation exacerbates interactions among the stimulation channels and limits cochlear implant outcome led to the breakthrough in the development of cochlear implants, the continuous interleaved (CIS) sampling coding strategy. By interleaving stimulation pulses across electrodes, CIS activates only a single electrode at each point in time, preventing a direct summation of electrical fields and hence the primary component of channel interactions. In this paper we show that a previously presented approach of simultaneous stimulation with channel interaction compensation (CIC) may also ameliorate the deleterious effects of simultaneous channel interaction on speech perception. In an acute study conducted in eleven experienced MED-EL implant users, configurations involving simultaneous stimulation with CIC and doubled pulse phase durations have been investigated. As pairs of electrodes were activated simultaneously and pulse durations were doubled, carrier rates remained the same. Comparison conditions involved both CIS and fine structure (FS) strategies, either with strictly sequential or paired-simultaneous stimulation. Results showed no statistical difference in the perception of sentences in noise and monosyllables for sequential and paired-simultaneous stimulation with doubled phase durations. This suggests that CIC can largely compensate for the effects of simultaneous channel interaction, for both CIS and FS coding strategies. A simultaneous stimulation paradigm has a number of potential advantages over a traditional sequential interleaved design. The flexibility gained when dropping the requirement of interleaving pulses across electrodes may be instrumental in designing coding strategies for a more accurate transmission of stimulus features such as temporal fine structure or interaural time delays to the auditory nerve. Also, longer pulse phase durations may be implemented while maintaining relatively high stimulation pulse rates. Utilizing longer pulse durations may relax requirements on implant compliance and facilitate the design of more energy-efficient implant receivers for a longer battery lifetime or a reduction in implant size. This article is part of a Special Issue entitled .

Recent animal studies have shown that the synapses between inner hair cells and the dendrites of the spiral ganglion cells they innervate are the elements in the cochlea most vulnerable to excessive noise exposure. Particularly in rodents, several studies have concluded that exposure to high level octave-band noise for 2 h leads to an irreversible loss of around 50% of synaptic ribbons, leaving audiometric hearing thresholds unaltered. Cochlear synaptopathy following noise exposure is hypothesized to degrade the neural encoding of sounds at the subcortical level, which would help explain certain listening-in-noise difficulties reported by some subjects with otherwise ‘normal’ hearing. In response to this peripheral damage, increased gain of central stages of the auditory system has been observed across several species of mammals, particularly in association with tinnitus. The auditory brainstem response (ABR) wave I amplitude and waves I-V amplitude ratio have been suggested as non-invasive indicators of cochlear synaptopathy and central gain activation respectively, but the evidence for these hearing disorders in humans is inconclusive. In this study, we evaluated the influence of lifetime noise exposure (LNE) on the human ABR and on speech-in-noise intelligibility performance in a large cohort of adults aged 29 to 55. Despite large inter-subject variability, results showed a moderate, but statistically significant, negative correlation between the ABR wave I amplitude and LNE, consistent with cochlear synaptopathy. The results also showed (a) that central gain mechanisms observed in animal studies might also occur in humans, in which higher stages of the auditory pathway appear to compensate for reduced input from the cochlea; (b) that tinnitus was associated with activation of central gain mechanisms; (c) that relevant cognitive and subcortical factors influence speech-in-noise intelligibility, in particular, longer ABR waves I-V interpeak latencies were associated with poorer performance in understanding speech in noise when central gain mechanisms were active; and (d) absence of a significant relationship between LNE and tinnitus, central gain activation or speech-in-noise performance. Although this study supports the possible existence of cochlear synaptopathy in humans, the great degree of variability, the lack of uniformity in central gain activation and the significant involvement of attention in speech-in-noise performance suggests that noise-induced cochlear synaptopathy is, at most, one of several factors that play a role in humans' speech-in-noise performance.

Music and language are two intricately linked communication modalities in humans. A deficit in music pitch processing as manifested in the condition of congenital amusia has been related to difficulties in lexical tone processing for both tone and non-tonal languages. However, it is still unclear whether amusia also affects the perception of vowel phonemes in quiet and in noise. In this study, we examined vowel-plus-tone identification in quiet and noise conditions among Mandarin-speaking amusics with and without speech tone difficulties (tone agnosics and pure amusics, respectively), and IQ- and age-matched controls. Overall, pure amusics showed vowel and tone identification comparable to the controls in both quiet and noise conditions. Compared to pure amusics and controls, tone agnosics showed deficits in tone perception in both quiet and noise conditions. More importantly, their vowel perception was lower than pure amusics and controls in noise conditions, e.g., at a signal-to-noise ratio of −4 dB, although they showed normal-like performance in quiet and at a signal-to-noise ratio of −8 dB. These results suggest that when amusia affected speech tone processing (e.g., tone agnosics), it could also compromise vowel processing in noise. However, amusia alone does not affect tone or vowel perception in Mandarin Chinese either in quiet or in noise. Overall, the current study highlights the necessity of taking heterogeneity within the amusic group into account when considering the related speech deficits in this group.

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.

The effort required to listen to and understand noisy speech is an important factor in the evaluation of noise reduction schemes. This paper introduces a model for Listening Effort prediction from Acoustic Parameters (LEAP). The model is based on methods from automatic speech recognition, specifically on performance measures that quantify the degradation of phoneme posteriorgrams produced by a deep neural net: Noise or artifacts introduced by speech enhancement often result in a temporal smearing of phoneme representations, which is measured by comparison of phoneme vectors. This procedure does not require a priori knowledge about the processed speech, and is therefore single-ended. The proposed model was evaluated using three datasets of noisy speech signals with listening effort ratings obtained from normal hearing and hearing impaired subjects. The prediction quality was compared to several baseline models such as the ITU-T standard P.563 for single-ended speech quality assessment, the American National Standard ANIQUE+ for single-ended speech quality assessment, and a single-ended SNR estimator. In all three datasets, the proposed new model achieved clearly better prediction accuracies than the baseline models; correlations with subjective ratings were above 0.9. So far, the model is trained on the specific noise types used in the evaluation. Future work will be concerned with overcoming this limitation by training the model on a variety of different noise types in a multi-condition way in order to make it generalize to unknown noise types.

Recent studies have shown that activating the noise reduction scheme in hearing aids results in a smaller peak pupil dilation (PPD), indicating reduced listening effort, at 50% and 95% correct sentence recognition with a 4-talker masker. The objective of this study was to measure the effect of the noise reduction scheme (on or off) on PPD and sentence recognition across a wide range of signal-to-noise ratios (SNRs) from +16 dB to −12 dB and two masker types (4-talker and stationary noise). Relatively low PPDs were observed at very low (−12 dB) and very high (+16 dB to +8 dB) SNRs presumably due to ‘giving up’ and ‘easy listening’, respectively. The maximum PPD was observed with SNRs at approximately 50% correct sentence recognition. Sentence recognition with both masker types was significantly improved by the noise reduction scheme, which corresponds to the shift in performance from SNR function at approximately 5 dB toward a lower SNR. This intelligibility effect was accompanied by a corresponding effect on the PPD, shifting the peak by approximately 4 dB toward a lower SNR. In addition, with the 4-talker masker, when the noise reduction scheme was active, the PPD was smaller overall than that when the scheme was inactive. We conclude that with the 4-talker masker, noise reduction scheme processing provides a listening effort benefit in addition to any effect associated with improved intelligibility. Thus, the effect of the noise reduction scheme on listening effort incorporates more than can be explained by intelligibility alone, emphasizing the potential importance of measuring listening effort in addition to traditional speech reception measures.

Unilateral hearing loss (UHL) occurs in 25% of cases of congenital sensorineural hearing loss. Due to the unilaterally reduced audibility associated with UHL, everyday demanding listening situations may be disrupted despite normal hearing in one ear. The aim of this study was to quantify acute changes in recognition of speech in spatially separate competing speech and sound localization accuracy, and relate those changes to two levels of temporary induced UHL (UHL30 and UHL43; suffixes denote the average hearing threshold across 0.5, 1, 2, and 4 kHz) for 8 normal-hearing adults. A within-subject repeated-measures design was used (normal binaural conditions, UHL30 and UHL43). The main outcome measures were the threshold for 40% correct speech recognition and the overall variance in sound localization accuracy quantified by an Error Index (0 = perfect performance, 1.0 = random performance). Distinct and statistically significant deterioration in speech recognition (2.0 dB increase in threshold, p 0.05), while sound localization was additionally impaired (Error Index increase of 0.33, p < 0.01) with an associated large increase in individual variability. Qualitative analyses on a subject-by-subject basis showed that high-frequency audibility was important for speech recognition, while low-frequency audibility was important for horizontal sound localization accuracy. While the data might not be entirely applicable to individuals with long-standing UHL, the results suggest a need for intervention for mild-to-moderate UHL.

Behavioral studies reveal listeners exploit intrinsic differences in voice fundamental frequency (F0) to segregate concurrent speech sounds-the so-called "F0-benefit." More favorable signal-to-noise ratio (SNR) in the environment, an extrinsic acoustic factor, similarly benefits the parsing of simultaneous speech. Here, we examined the neurobiological substrates of these two cues in the perceptual segregation of concurrent speech mixtures. We recorded event-related brain potentials (ERPs) while listeners performed a speeded double-vowel identification task. Listeners heard two concurrent vowels whose F0 differed by zero or four semitones presented in either clean (no noise) or noise-degraded (+5 dB SNR) conditions. Behaviorally, listeners were more accurate in correctly identifying both vowels for larger F0 separations but F0-benefit was more pronounced at more favorable SNRs (i.e., pitch × SNR interaction). Analysis of the ERPs revealed that only the P2 wave (∼200 ms) showed a similar F0 x SNR interaction as behavior and was correlated with listeners' perceptual F0-benefit. Neural classifiers applied to the ERPs further suggested that speech sounds are segregated neurally within 200 ms based on SNR whereas segregation based on pitch occurs later in time (400-700 ms). The earlier timing of extrinsic SNR compared to intrinsic F0-based segregation implies that the cortical extraction of speech from noise is more efficient than differentiating speech based on pitch cues alone, which may recruit additional cortical processes. Findings indicate that noise and pitch differences interact relatively early in cerebral cortex and that the brain arrives at the identities of concurrent speech mixtures as early as ∼200 ms.

In noisy listening conditions, intelligibility of degraded speech can be enhanced by top-down restoration. Cochlear implant (CI) users have difficulty understanding speech in noisy environments. This could partially be due to reduced top-down restoration of speech, which may be related to the changes that the electrical stimulation imposes on the bottom-up cues. We tested this hypothesis using the phonemic restoration (PhR) paradigm in which speech interrupted with periodic silent intervals is perceived illusorily continuous (continuity illusion or Col) and becomes more intelligible (PhR benefit) when the interruptions are filled with noise bursts. Using meaningful sentences, both Col and PhR benefit were measured in CI users, and compared with those of normal-hearing (NH) listeners presented with normal speech and 8-channel noise-band vocoded speech, acoustically simulating CIs. CI users showed different patterns in both PhR benefit and Col, compared to NH results with or without the noise-band vocoding. However, they were able to use top-down restoration under certain test conditions. This observation supports the idea that changes in bottom-up cues can impose changes to the top down processes needed to enhance intelligibility of degraded speech. The knowledge that CI users seem to be able to do restoration under the right circumstances could be exploited in patient rehabilitation and product development. (C) 2013 Elsevier B.V. All rights reserved.

We investigated gender differences in the identification of personally familiar voices in a gender-balanced sample of 40 listeners. From various types of utterances, listeners had to identify by name 20 speakers (10 female) among a set of 70 possible classmates who were all 12th grade pupils from the same local secondary school. Mean identification rates were 67% from sentences, and around 35% for an isolated /Hello/ or a VCV syllable. Even from non-verbal harrumphs, speakers were identified with an accuracy of 18%, i.e. highly above chance levels. Substantial individual differences were observed between listeners. Importantly, superior overall performance of female listeners was qualified by an interaction between voice gender and listener gender. Male listeners exhibited an own-gender bias (i.e. better identification for male than female voices), whereas female listeners identified voices of both genders at similar levels. Individual own-gender identification biases were correlated with differences in reported contact to a speaker's voice and voice distinctiveness. Overall, the present study establishes a number of factors that account for substantial individual differences in personal voice identification.

Item does not contain fulltext Since deafness is the most common sensorineural disorder in humans, better understanding of the underlying causes is necessary to improve counseling and rehabilitation. A Dutch family with autosomal dominantly inherited sensorineural hearing loss was clinically and genetically assessed. The MYO6 gene was selected to be sequenced because of similarities with other, previously described DFNA22 phenotypes and a pathogenic c.3610C > T (p.R1204W) mutation was found to co-segregate with the disease. This missense mutation results in a flat configured audiogram with a mild hearing loss, which becomes severe to profound and gently to steeply downsloping later in life. The age-related typical audiograms (ARTA) constructed for this family resemble presbyacusis. Speech audiometry and results of loudness scaling support the hypothesis that the phenotype of this specific MYO6 mutation mimics presbyacusis.

This study explored the effects on speech intelligibility of across-formant differences in fundamental frequency (ΔF0) and F0 contour. Sentence-length speech analogues were presented dichotically (left = F1+F3; right = F2), either alone or-because competition usually reveals grouping cues most clearly-accompanied in the left ear by a competitor for F2 (F2C) that listeners must reject to optimize recognition. F2C was created by inverting the F2 frequency contour. In experiment 1, all left-ear formants shared the same constant F0 and ΔF0

Speech understanding in the presence of concurring sound is a major challenge especially for older persons. In particular, conversational turn-takings usually result in switch costs, as indicated by declined speech perception after changes in the relevant target talker. Here, we investigated whether visual cues indicating the future position of a target talker may reduce the costs of switching in younger and older adults. We employed a speech perception task, in which sequences of short words were simultaneously presented by three talkers, and analysed behavioural measures and event-related potentials (ERPs). Informative cues resulted in increased performance after a spatial change in target talker compared to uninformative cues, not indicating the future target position. Especially the older participants benefited from knowing the future target position in advance, indicated by reduced response times after informative cues. The ERP analysis revealed an overall reduced N2, and a reduced P3b to changes in the target talker location in older participants, suggesting reduced inhibitory control and context updating. On the other hand, a pronounced frontal late positive complex (f-LPC) to the informative cues indicated increased allocation of attentional resources to changes in target talker in the older group, in line with the decline-compensation hypothesis. Thus, knowing where to listen has the potential to compensate for age-related decline in attentional switching in a highly variable cocktail-party environment.

A prominent feature of the auditory system is that neurons show tuning to audio frequency; each neuron has a characteristic frequency (CF) to which it is most sensitive. Furthermore, there is an orderly mapping of CF to position, which is called tonotopic organization and which is observed at many levels of the auditory system. In a previous study (Thwaites et al., 2016) we examined cortical entrainment to two auditory transforms predicted by a model of loudness, instantaneous loudness and short-term loudness, using speech as the input signal. The model is based on the assumption that neural activity is combined across CFs (i.e. across frequency channels) before the transform to short-term loudness. However, it is also possible that short-term loudness is determined on a channel-specific basis. Here we tested these possibilities by assessing neural entrainment to the overall and channel-specific instantaneous loudness and the overall and channel-specific short-term loudness. The results showed entrainment to channel-specific instantaneous loudness at latencies of 45 and 100 ms (bilaterally, in and around Heschl's gyrus). There was entrainment to overall instantaneous loudness at 165 ms in dorso-lateral sulcus (DLS). Entrainment to overall short-term loudness occurred primarily at 275 ms, bilaterally in DLS and superior temporal sulcus. There was only weak evidence for entrainment to channel-specific short-term loudness., Highlights • The latency of cortical entrainment to various aspects of loudness was assessed. • For channel-specific instantaneous loudness the latencies were 45 and 100 ms. • For overall instantaneous loudness the latency was 165 ms. • For overall short-term loudness the latency was 275 ms. • Entrainment to channel-specific short-term loudness was weak.

Differences in fundamental frequency (F0) between voiced sounds are known to be a strong cue for stream segregation. However, speech consists of both voiced and unvoiced sounds, and less is known about whether and how the unvoiced portions are segregated. This study measured listeners’ ability to integrate or segregate sequences of consonant-vowel tokens, comprising a voiceless fricative and a vowel, as a function of the F0 difference between interleaved sequences of tokens. A performance-based measure was used, in which listeners detected the presence of a repeated token either within one sequence or between the two sequences (measures of voluntary and obligatory streaming, respectively). The results showed a systematic increase of voluntary stream segregation as the F0 difference between the two interleaved sequences increased from 0 to 13 semitones, suggesting that F0 differences allowed listeners to segregate speech sounds, including the unvoiced portions. In contrast to the consistent effects of voluntary streaming, the trend towards obligatory stream segregation at large F0 differences failed to reach significance. Listeners were no longer able to perform the voluntary-streaming task reliably when the unvoiced portions were removed from the stimuli, suggesting that the unvoiced portions were used and correctly segregated in the original task. The results demonstrate that streaming based on F0 differences occurs for natural speech sounds, and that unvoiced portions are correctly assigned to corresponding voiced portions of the speech sounds.

As people grow older, speech perception difficulties become highly prevalent, especially in noisy listening situations. Moreover, it is assumed that speech intelligibility is more affected in the event of background noises that induce a higher cognitive load, i.e., noises that result in informational versus energetic masking. There is ample evidence showing that speech perception problems in aging persons are partly due to hearing impairment and partly due to age-related declines in cognition and suprathreshold auditory processing. In order to develop effective rehabilitation strategies, it is indispensable to know how these different degrading factors act upon speech perception. This implies disentangling effects of hearing impairment versus age and examining the interplay between both factors in different background noises of everyday settings. To that end, we investigated open-set sentence identification in six participant groups: a young (20–30 years), middle-aged (50–60 years), and older cohort (70–80 years), each including persons who had normal audiometric thresholds up to at least 4 kHz, on the one hand, and persons who were diagnosed with elevated audiometric thresholds, on the other hand. All participants were screened for (mild) cognitive impairment. We applied stationary and amplitude modulated speech-weighted noise, which are two types of energetic maskers, and unintelligible speech, which causes informational masking in addition to energetic masking. By means of these different background noises, we could look into speech perception performance in listening situations with a low and high cognitive load, respectively. Our results indicate that, even when audiometric thresholds are within normal limits up to 4 kHz, irrespective of threshold elevations at higher frequencies, and there is no indication of even mild cognitive impairment, masked speech perception declines by middle age and decreases further on to older age. The impact of hearing impairment is as detrimental for young and middle-aged as it is for older adults. When the background noise becomes cognitively more demanding, there is a larger decline in speech perception, due to age or hearing impairment. Hearing impairment seems to be the main factor underlying speech perception problems in background noises that cause energetic masking. However, in the event of informational masking, which induces a higher cognitive load, age appears to explain a significant part of the communicative impairment as well. We suggest that the degrading effect of age is mediated by deficiencies in temporal processing and central executive functions. This study may contribute to the improvement of auditory rehabilitation programs aiming to prevent aging persons from missing out on conversations, which, in turn, will improve their quality of life.

Military personnel are at risk for hearing loss due to noise exposure during deployment (USACHPPM, 2008). Despite mandated use of hearing protection, hearing loss and tinnitus are prevalent due to reluctance to use hearing protection. Bone conduction headsets can offer good speech intelligibility for normal hearing (NH) listeners while allowing the ears to remain open in quiet environments and the use of hearing protection when needed. Those who suffer from tinnitus, the experience of perceiving a sound not produced by an external source, often show degraded speech recognition; however, it is unclear whether this is a result of decreased hearing sensitivity or increased distractibility (Moon et al., 2015). It has been suggested that the vibratory stimulation of a bone conduction headset might ameliorate the effects of tinnitus on speech perception; however, there is currently no research to support or refute this claim (Hoare et al., 2014). Speech recognition of words presented over air conduction and bone conduction headsets was measured for three groups of listeners: NH, sensorineural hearing impaired, and/or tinnitus sufferers. Three levels of speech-to-noise (SNR = 0, -6, -12 dB) were created by embedding speech items in pink noise. Better speech recognition performance was observed with the bone conduction headset regardless of hearing profile, and speech intelligibility was a function of SNR. Discussion will include study limitations and the implications of these findings for those serving in the military.

Military Service Members are often exposed to high levels of occupational noise, solvents, and other exposures that can be damaging to the auditory system. Little is known about hearing loss and how it progresses in Veterans following military service. This epidemiology study is designed to evaluate and monitor a cohort of Veterans for 20 years or more to determine how hearing loss changes over time and how those changes are related to noise exposure and other ototoxic exposures encountered during military service. Data reported here are from baseline assessments of the first 100 study participants (84 males; 16 females; mean age 33.5 years; SD 8.8; range 21–58). Each participant was asked to complete a comprehensive audiologic examination and self-report questionnaires regarding sociodemographic characteristics, noise and solvent exposures, health conditions common among post-deployment Veterans, and the social and emotional consequences of hearing loss. For this relatively young cohort, 29% exhibited hearing loss, defined as average hearing threshold >20 dB HL in the conventional audiometric range. Forty-two percent exhibited hearing loss in the extended-high-frequency audiometric range using the same criterion (average hearing threshold >20 dB HL). Certain factors were found to be associated with poorer hearing in both conventional and extended-high-frequency ranges, including age, type of military branch, years of military service, number of military deployments, noise exposure, tinnitus, and a positive screen for post-traumatic stress disorder. Although the majority of participants had hearing within normal limits, 27% reported a self-perceived mild/moderate hearing handicap and 14% reported a significant handicap. Further research is needed to identify a cause for this discrepancy in audiologic results versus self-report. The information obtained from this longitudinal study could be used in future resource planning with the goal of preventing, as much as possible, the development of hearing loss during military service, and the exacerbation of prevalent hearing loss after military service and over Veterans' lifetimes.

Sound coding strategies for Cochlear Implant (CI) listeners can be used to control the trade-off between speech performance and power consumption. Most commercial CI strategies use non-simultaneous channel stimulation, stimulating only one electrode at a time. One could add parallel simultaneous stimulating channels such that the electrical interaction between channels is increased. This would produce spectral smearing, because the electrical fields of the simultaneous stimulated channels interact, but also power savings. The parallel channels produce a louder sensation than sequential stimulation. To test this hypothesis we implemented different sound coding strategies using a research interface from Advanced Bionics: the commercial F120 strategy using sequential channel stimulation (one channel equals two electrodes with current steering) and the Paired strategy, consisting of simultaneous stimulation with two channels. Here, the electrical field of both channels will interact, requiring less current on each channel to perceive the same loudness as with F120. However, channel interaction between the independent channels may reduce speech recognition or understanding. This can be diminished by adding an inverse-polarity stimulation channel between both channels. This strategy is termed Paired with Flanks. Additionally, Triplet with three channels and an adjacent Flank style was investigated. For each strategy we measured speech intelligibility with the Hochmair-Schulz-Moser sentence test. Spectral resolution was assessed using a spectral modulation depth detection task. Results show that Paired without Flanks obtains similar performance while reducing the current by 20% on average compared to F120. Triplet with and without Flanks shows overall poorer performance when compared to F120. All strategies inhibit the option to increase the pulse width which would result in even further decreased power consumption.

Item does not contain fulltext OBJECTIVE: To evaluate hearing impairment and cochlear function in non-ocular Stickler syndrome. STUDY DESIGN: Multifamily study. PATIENTS & METHODS: Ten patients from two different families with non-ocular Stickler syndrome (Stickler syndrome type 3) were included. Six members of the first family and four members of the second family participated in this study. Otorhinolaryngologic examinations were performed. Pure-tone and speech audiograms were obtained. Longitudinal analysis was performed. Psychophysical measurements, including loudness scaling, gap detection, difference limen for frequency and speech perception in noise were administered to assess cochlear function at a deeper level. RESULTS: Affected individuals in the first family were carriers of a heterozygous splice donor mutation in the COL11A2 gene. Affected individuals in the second family were carriers of a novel heterozygous missense mutation in COL11A2. Both families showed bilateral, non-progressive hearing impairment with childhood onset. The severity of the hearing impairment exhibited inter- and intrafamilial variability and was mostly mild to moderate. The results of the psychophysical measurements were similar to those previously published for DFNA8/12 (TECTA) and DFNA13 (COL11A2) patients and thus consistent with an intra-cochlear conductive hearing impairment. This is in line with the theory that mutations in COL11A2 affect tectorial membrane function. CONCLUSION: Hearing impairment in non-ocular Stickler syndrome is characterized by non-progressive hearing loss, present since childhood, and mostly mild to moderate in severity. Psychophysical measurements in non-ocular Stickler patients were suggestive of intra-cochlear conductive hearing impairment. 01 september 2012

Presenting the early part of a nonsense sentence in quiet improves recognition of the last keyword of the sentence in a masker, especially a speech masker. This priming effect depends on higher-order processing of the prime information during target-masker segregation. This study investigated whether introducing irrelevant content information into the prime reduces the priming effect. The results showed that presenting the first four syllables (not including the second and third keywords) of the three-keyword target sentence in quiet significantly improved recognition of the second and third keywords in a two-talker-speech masker but not a noise masker, relative to the no-priming condition. Increasing the prime content from four to eight syllables (including the first and second keywords of the target sentence) further improved recognition of the third keyword in either the noise or speech masker. However, if the last four syllables of the eight-syllable prime were replaced by four irrelevant syllables (which did not occur in the target sentence), all the prime-induced speech-recognition improvements disappeared. Thus, knowing the early part of the target sentence mainly reduces informational masking of target speech, possibly by helping listeners attend to the target speech. Increasing the informative content of the prime further improves target-speech recognition probably by reducing the processing load. The reduction of the priming effect by adding irrelevant information to the prime is not due to introducing additional masking of the target speech.

The addition of background noise to an auditory signal delays brainstem response timing. This effect has been extensively documented using manual peak selection. Peak picking, however, is impractical for large-scale studies of spectrotemporally complex stimuli, and leaves open the question of whether noise-induced delays are frequency-dependent or occur across the frequency spectrum. Here we use an automated, objective method to examine phase shifts between auditory brainstem responses to a speech sound (/da/) presented with and without background noise. We predicted that shifts in neural response timing would also be reflected in frequency-specific phase shifts. Our results indicate that the addition of background noise causes phase shifts across the subcortical response spectrum (70 – 1000Hz). However, this noise-induced delay is not uniform such that some frequency bands show greater shifts than others: low-frequency phase shifts (300–500 Hz) are largest during the response to the consonant-vowel formant transition (/d/), while high-frequency shifts (720–1000 Hz) predominate during the response to the steady-state vowel (/a/). Most importantly, phase shifts occurring in specific frequency bands correlate strongly with shifts in the latencies of the predominant peaks in the auditory brainstem response, while other frequency bands do not correlate with latency shifts. This finding confirms the validity of phase shift detection as an objective measure of timing differences and reveals that this method detects noise-induced shifts in timing that may not be captured by traditional peak latency measurements.

High-level adaptation not only biases the perception of faces, but also causes transient distortions in auditory perception of non-linguistic voice information about gender, identity, and emotional intonation. Here we report a novel auditory aftereffect in perceiving vocal age: age estimates were elevated in age-morphed test voices when preceded by adaptor voices of young speakers (∼20 yrs), compared to old adaptor voices (∼70 yrs). This vocal age aftereffect (VAAE) complements a recently reported face aftereffect (Schweinberger et al., 2010) and points to selective neuronal coding of vocal age. Intriguingly, post-adaptation assessment revealed that VAAEs could persist for minutes after adaptation, although reduced in magnitude. As an important qualification, VAAEs during post-adaptation were modulated by gender congruency between speaker and listener. For both male and female listeners, VAAEs were much reduced for test voices of opposite gender. Overall, this study establishes a new auditory aftereffect in the perception of vocal age. We offer a tentative sociobiological explanation for the differential, gender-dependent recovery from vocal age adaptation.

Improvements in speech-recognition performance resulting from the addition of low-frequency information to electric (or vocoded) signals have attracted considerable interest in recent years. An important question is whether these improvements reflect a form of constructive perceptual interaction—whereby acoustic cues enhance the perception of electric or vocoded signals—or whether they can be explained without assuming any interaction. To address this question, speech-recognition performance was measured in 24 normal-hearing listeners using lowpass-filtered, vocoded, and “combined” (lowpass + vocoded) words presented either in quiet or in a realistic background (cafeteria noise), for different signal-to-noise ratios, different lowpass-filter cutoff frequencies, and different numbers of vocoder bands. The results of these measures were then compared to the predictions of three models of cue combination, including a “probability-summation” model and two Gaussian signal detection theory (SDT) models—one (the “independent-noises” model) involving pre-combination noises, and the other (the “late-noise” model) involving post-combination noise. Consistent with previous findings, speech-recognition performance with combined stimulation was significantly higher than performance with vocoded or lowpass stimuli alone, and it was also higher than predicted by the probability-summation model. The two Gaussian-SDT models could account quantitatively for the data. Moreover, a Bayesian model-comparison procedure demonstrated that, given the data, these two models were far more likely than the probability-summation model. Since these models do not involve any constructive-interaction mechanism, this demonstrates that constructive interactions are not needed to explain the combined-stimulation benefits measured in this study. It will be important for future studies to investigate whether this conclusion generalizes to other test conditions, including real EAS, and to further test the assumptions of these different models of the combined-stimulation advantage.

The present study used eight normal-hearing (NH) subjects, listening to acoustic cochlear implant (CI) simulations, to examine the effects of spectral shifting on speech recognition in noise. Speech recognition was measured using spectrally matched and shifted speech (vowels, consonants, and IEEE sentences), generated by 8-channel, sine-wave vocoder. Measurements were made in quiet and in noise (speech-shaped static noise and speech-babble at 5 dB signal-to-noise ratio). One spectral match condition and four spectral shift conditions were investigated: 2 mm, 3 mm, and 4 mm linear shift, and 3 mm shift with compression, in terms of cochlear distance. Results showed that speech recognition scores dropped because of noise and spectral shifting, and that the interactive effects of spectral shifting and background conditions depended on the degree/type of spectral shift, background conditions, and the speech test materials. There was no significant interaction between spectral shifting and two noise conditions for all speech test materials. However, significant interactions between linear spectral shifts and all background conditions were found in sentence recognition; significant interactions between spectral shift types and all background conditions were found in vowel recognition. Overall, the results suggest that tonotopic mismatch may affect performance of CI users in complex listening environments.

This study evaluated unmasking functions of perceptual integration of target speech and simulated target-speech reflection, which were presented by two spatially separated loudspeakers. In both younger-adult listeners with normal hearing and older-adult listeners in the early stages of presbycusis, reducing the time interval between target speech and target-reflection simulation (inter-target interval, ITI) from 64 to 0 ms not only progressively enhanced perceptual integration of target-speech signals, but also progressively released target speech from either speech masking or noise masking. When the signal-to-noise ratio was low, the release from speech masking was significantly larger than the release from noise masking in both younger listeners and older listeners, but the longest ITI at which a significant release from speech masking occurred was significantly shorter in older listeners than in younger listeners. These results suggest that in reverberant environments with multi-talker speech, perceptual integration between the direct sound wave and correlated reflections, which facilitates perceptual segregation of various sources, is critical for unmasking attended speech. The age-related reduction of the ITI range for releasing speech from speech masking may be one of the causes for the speech-recognition difficulties experienced by older listeners in such adverse environments.

Consonant identification was measured for normal-hearing listeners using nonsense Vowel-Consonant-Vowel (VCV) stimuli embedded in a steady-state or fluctuating noise masker and presented at a fixed, global signal-to-noise ratio (SNR) yielding 50% correct identification for steady noise. Fluctuations in the masker were obtained by applying sinusoidal amplitude modulation to the noise. VCVs and noise were either left intact (unprocessed) or degraded by removing temporal fine structure (TFS) cues within 32 frequency bands with bandwidths chosen to match psychophysical estimates of auditory filter bandwidth. For unprocessed stimuli, masking release (MR) - that is better identification in fluctuating than in steady noise - was observed at both masker frequencies tested (8 and 32 Hz). MR increased monotonically and similarly with the modulation depth m of the noise masker (from m=12.5% to 100%) at both masker modulation frequencies. The effect of masker modulation depth on release was different for reception of place of articulation and reception of voicing and manner. The effect of masker modulation depth on release was also significantly affected when TFS cues were removed. These data provide evidence that listeners "glimpse" into noise valleys where maximum SNR may be as low as -5 dB (m=12.5%), and suggest a specific contribution of TFS cues to the glimpsing process.

The purpose of this study was to examine the relationship between English vowel identification and English vowel formant discrimination for native Mandarin Chinese- and native English-speaking listeners. The identification of 12 English vowels was measured with the duration cue preserved or removed. The thresholds of vowel formant discrimination on the F2 of two English vowels,/Λ/and/i/, were also estimated using an adaptive-tracking procedure. Native Mandarin Chinese-speaking listeners showed significantly higher thresholds of vowel formant discrimination and lower identification scores than native English-speaking listeners. The duration effect on English vowel identification was similar between native Mandarin Chinese- and native English-speaking listeners. Moreover, regardless of listeners' language background, vowel identification was significantly correlated with vowel formant discrimination for the listeners who were less dependent on duration cues, whereas the correlation between vowel identification and vowel formant discrimination was not significant for the listeners who were highly dependent on duration cues. This study revealed individual variability in using multiple acoustic cues to identify English vowels for both native and non-native listeners.

In complex listening situations, cognitive restoration mechanisms are commonly used to enhance perception of degraded speech with inaudible segments. Profoundly hearing-impaired people with a cochlear implant (Cl) show less benefit from such mechanisms. However, both normal hearing (NH) listeners and CI users do benefit from visual speech cues in these listening situations. In this study we investigated if an accompanying video of the speaker can enhance the intelligibility of interrupted sentences and the phonemic restoration benefit, measured by an increase in intelligibility when the silent intervals are filled with noise. Similar to previous studies, restoration benefit was observed with interrupted speech without spectral degradations (Experiment 1), but was absent in acoustic simulations of CIs (Experiment 2) and was present again in simulations of electric-acoustic stimulation (Experiment 3). In all experiments, the additional speech information provided by the complementary visual cues lead to overall higher intelligibility, however, these cues did not influence the occurrence or extent of the phonemic restoration benefit of filler noise. Results imply that visual cues do not show a synergistic effect with the filler noise, as adding them equally increased the intelligibility of interrupted sentences with or without the filler noise. (C) 2015 Elsevier B.V. All rights reserved.

A consonant identification test was carried out with 10 hearing-impaired listeners under various low-pass filter conditions. Subjects were also tested for cochlear dead regions with the TEN test. All subjects had moderate-to-severe high-frequency hearing losses. Consonant recognition was tested under conditions in which the speech signals were highly audible to subjects for frequencies up to the low-pass filter cut-off. Extensive dead regions were found for one subject with the TEN test. The remaining subjects may have had dead regions above 3 kHz, because of the severity of their hearing losses, but these could not be demonstrated with the TEN test. Average consonant scores for the subject group improved significantly (p < 0.05) with increasing audibility of high-frequency components of the speech signal. There were no cases of speech perception being reduced with increasing bandwidth. Nine of the subjects showed improvements in scores with increasing audibility, whereas the remaining subject showed little change in scores. For this subject, speech perception results were consistent with the TEN test findings. In general, the results suggest that listeners with severe high-frequency losses are often able to make some use of high-frequency speech cues if these cues can be made audible.

In the brain, the temporal analysis of many important auditory features relies on the synchronized firing of neurons to the auditory input rhythm. These so-called neural oscillations play a crucial role in sensory and cognitive processing and deviances in oscillatory activity have shown to be associated with neurodevelopmental disorders. Given the importance of neural auditory oscillations in normal and impaired sensory and cognitive functioning, there has been growing interest in their developmental trajectory from early childhood on. In the present study, neural auditory processing was investigated in typically developing young children (n = 40) and adults (n = 27). In all participants, auditory evoked theta, beta and gamma responses were recorded. The results of this study show maturational differences between children and adults in neural auditory processing at cortical as well as at brainstem level. Neural background noise at cortical level was shown to be higher in children compared to adults. In addition, higher theta response amplitudes were measured in children compared to adults. For beta and gamma rate modulations, different processing asymmetry patterns were observed between both age groups. The mean response phase was also shown to differ significantly between children and adults for all rates. Results suggest that cortical auditory processing of beta develops from a general processing pattern into a more specialized asymmetric processing preference over age. Moreover, the results indicate an enhancement of bilateral representation of monaural sound input at brainstem with age. A dissimilar efficiency of auditory signal transmission from brainstem to cortex along the auditory pathway between children and adults is suggested. These developmental differences might be due to both functional experience-dependent as well as anatomical changes. The findings of the present study offer important information about maturational differences between children and adults for responses to theta, beta and gamma rates. The current study can have important implications for the understanding of developmental disorders which are known to be associated with deviances in neural auditory processing. publisher: Elsevier articletitle: Theta, beta and gamma rate modulations in the developing auditory system journaltitle: Hearing Research articlelink: http://dx.doi.org/10.1016/j.heares.2015.06.011 content_type: article copyright: Copyright © 2015 Elsevier B.V. All rights reserved. ispartof: Hearing Research vol:327 pages:153-162 ispartof: location:Netherlands status: published

This study explored the role of formant transitions and F0-contour continuity in binding together speech sounds into a coherent stream. Listening to a repeating recorded word produces verbal transformations to different forms; stream segregation contributes to this effect and so it can be used to measure changes in perceptual coherence. In experiment 1, monosyllables with strong formant transitions between the initial consonant and following vowel were monotonized; each monosyllable was paired with a weak-transitions counterpart. Further stimuli were derived by replacing the consonant-vowel transitions with samples from adjacent steady portions. Each stimulus was concatenated into a 3-min-long sequence. Listeners only reported more forms in the transitions-removed condition for strong-transitions words, for which formant-frequency discontinuities were substantial. In experiment 2, the F0 contour of all-voiced monosyllables was shaped to follow a rising or falling pattern, spanning one octave. Consecutive tokens either had the same contour, giving an abrupt F0 change between each token, or alternated, giving a continuous contour. Discontinuous sequences caused more transformations and forms, and shorter times to the first transformation. Overall, these findings support the notion that continuity cues provided by formant transitions and the F0 contour play an important role in maintaining the perceptual coherence of speech.

Item does not contain fulltext A total of 64 loci for autosomal dominant non-syndromic hearing impairment have been described, and the causative genes have been identified for 24 of these. The present study reports on the clinical characteristics of an autosomal dominantly inherited hearing impairment that is linked to a region within the DFNA60 locus located on chromosome 2 in q22.1-24.1. A pedigree spanning four generations was established with 13 affected individuals. Linkage analysis demonstrated that the locus extended over a 2.96 Mb region flanked by markers D2S2335 and D2S2275. The audiograms mainly showed a distinctive U-shaped configuration. Deterioration of hearing started at a wide age range, from 12 to 40 years. Cross-sectional analysis showed rapid progression of hearing impairment from mild to severe, between the ages of 40 and 60 years, a phenomenon that is also observed in DFNA9 patients. The results of the individual longitudinal analyses were generally in line with those obtained by the cross-sectional analysis. Speech recognition scores related to the level of hearing impairment (PTA1,2,4 kHz) appeared to be fairly similar to those of presbyacusis patients. It is speculated that hearing impairment starting in mid-life, as shown by DFNA60 patients, could play a role in the development of presbyacusis. Furthermore, speech recognition did not deteriorate appreciably before the sixth decade of life. We conclude that DFNA60 should be considered in hearing impaired patients who undergo a rapid progression in middle age and are negative for DFNA9. Furthermore, cochlear implantation resulted in good rehabilitation in two DFNA60 patients.