Speech Perception Problems Research Articles

Speech perception deficits and the effect of envelope-enhanced story listening combined with phonics intervention in pre-readers at risk for dyslexia.

Developmental dyslexia is considered to be most effectively addressed with preventive phonics-based interventions, including grapheme-phoneme coupling and blending exercises. These intervention types require intact speech perception abilities, given their large focus on exercises with auditorily presented phonemes. Yet some children with (a risk for) dyslexia experience problems in this domain due to a poorer sensitivity to rise times, i.e., rhythmic acoustic cues present in the speech envelope. As a result, the often subtle speech perception problems could potentially constrain an optimal response to phonics-based interventions in at-risk children. The current study therefore aimed (1) to extend existing research by examining the presence of potential speech perception deficits in pre-readers at cognitive risk for dyslexia when compared to typically developing peers and (2) to explore the added value of a preventive auditory intervention for at-risk pre-readers, targeting rise time sensitivity, on speech perception and other reading-related skills. To obtain the first research objective, we longitudinally compared speech-in-noise perception between 28 5-year-old pre-readers with and 30 peers without a cognitive risk for dyslexia during the second half of the third year of kindergarten. The second research objective was addressed by exploring growth in speech perception and other reading-related skills in an independent sample of 62 at-risk 5-year-old pre-readers who all combined a 12-week preventive phonics-based intervention (GraphoGame-Flemish) with an auditory story listening intervention. In half of the sample, story recordings contained artificially enhanced rise times (GG-FL_EE group, n = 31), while in the other half, stories remained unprocessed (GG-FL_NE group, n = 31; Clinical Trial Number S60962-https://www.uzleuven.be/nl/clinical-trial-center). Results revealed a slower speech-in-noise perception growth in the at-risk compared to the non-at-risk group, due to an emerged deficit at the end of kindergarten. Concerning the auditory intervention effects, both intervention groups showed equal growth in speech-in-noise perception and other reading-related skills, suggesting no boost of envelope-enhanced story listening on top of the effect of combining GraphoGame-Flemish with listening to unprocessed stories. These findings thus provide evidence for a link between speech perception problems and dyslexia, yet do not support the potential of the auditory intervention in its current form.

Modelling representations in speech normalization of prosodic cues

The lack of invariance problem in speech perception refers to a fundamental problem of how listeners deal with differences of speech sounds produced by various speakers. The current study is the first to test the contributions of mentally stored distributional information in normalization of prosodic cues. This study starts out by modelling distributions of acoustic cues from a speech corpus. We proceeded to conduct three experiments using both naturally produced lexical tones with estimated distributions and manipulated lexical tones with f0 values generated from simulated distributions. State of the art statistical techniques have been used to examine the effects of distribution parameters in normalization and identification curves with respect to each parameter. Based on the significant effects of distribution parameters, we proposed a probabilistic parametric representation (PPR), integrating knowledge from previously established distributions of speakers with their indexical information. PPR is still accessed during speech perception even when contextual information is present. We also discussed the procedure of normalization of speech signals produced by unfamiliar talker with and without contexts and the access of long-term stored representations.

Talker familiarity and the accommodation of talker variability.

A fundamental problem in speech perception is how (or whether) listeners accommodate variability in the way talkers produce speech. One view of the way listeners cope with this variability is that talker differences are normalized - a mapping between talker-specific characteristics and phonetic categories is computed such that speech is recognized in the context of the talker's vocal characteristics. Consistent with this view, listeners process speech more slowly when the talker changes randomly than when the talker remains constant. An alternative view is that speech perception is based on talker-specific auditory exemplars in memory clustered around linguistic categories that allow talker-independent perception. Consistent with this view, listeners become more efficient at talker-specific phonetic processing after voice identification training. We asked whether phonetic efficiency would increase with talker familiarity by testing listeners with extremely familiar talkers (family members), newly familiar talkers (based on laboratory training), and unfamiliar talkers. We also asked whether familiarity would reduce the need for normalization. As predicted, phonetic efficiency (word recognition in noise) increased with familiarity (unfamiliar < trained-on < family). However, we observed a constant processing cost for talker changes even for pairs of family members. We discuss how normalization and exemplar theories might account for these results, and constraints the results impose on theoretical accounts of phonetic constancy.

Acoustical and Perceptual Analysis of Noise Reduction Strategies in Individuals With Auditory Neuropathy Spectrum Disorders.

Purpose The conventional amplification devices render minimal or no benefit at abating the speech perception problems of individuals with auditory neuropathy spectrum disorder (ANSD). This study was undertaken to evaluate the effect of noise reduction strategies (multiband spectral subtraction, Wiener-as, Karhunen-Loeve transform [Subspace], and ideal binary mask [IdBM] algorithm) on speech using speech perception measures and acoustic measure among individuals with ANSD. Method Two groups of participants (age: 17-43 years) were recruited in the study. Group I comprised 12 individuals with a confirmed diagnosis of ANSD and not exceeding moderate degree of hearing loss and Group II of 10 individuals with normal hearing in both ears. The signal-to-noise required for 50% speech recognition (SNR-50) was measured for the participants in five conditions, that is, unprocessed speech and speech processed with four noise reduction strategies. Additionally, an acoustic objective measure Extended Short-Time Objective Intelligibility algorithm was employed to estimate the intelligibility index across the conditions. Results Significant difference was found across conditions in both the groups. Pairwise comparison revealed significantly better speech perception on SNR-50 measure with IdBM strategy, for both the groups. No significant difference in SNR-50 was observed with other noise reduction strategies. IdBM condition also gave the highest intelligibility index (d) values using Extended Short-Time Objective Intelligibility algorithm. This finding needs to be verified on a larger group of individuals with ANSD. Conclusions IdBM noise reduction strategy rendered significantly lower SNR-50 compared to other noise reduction strategies for individuals with ANSD in this study. This provides clinical evidence for the same and also recommends trying on a larger group of participants before its implementation in hearing devices. Apart from this, the current strategies used in hearing aids provide no improvement in speech identification in noise for this population. Hence, though the present hearing aids may show benefit in quiet condition, chances of its rejection are high in noisy backgrounds.

Speech perception in children with reading disabilities: Phonetic perception is the problem

Reading disability (RD) is widely accepted as a key obstacle in the development of literacy. Studies show that 15–20% of grade-school students are RD. Many quit high-school and go to jail. We shall show that RD for 8–12 yrs is related to inadequate phonetic identification ability, rooted in pre-school language development. We used two tests (10 thousand responses/child): (1) A 3-interval forced choice procedure (Syllable Confusion Oddball Task: SCO). (2) A single CV/VC presentation task with oral response, to label CV/VC phones (Nonsense Syllable Confusion Matrix: NSCM). The experimental results showed that for the SCO task the 10 RD cohort had, on average 5 times the error compared to the 6 RC reading control (RC) cohort. The errors were highly idiosyncratic, analyzed by logit. (1) RDs have significant speech perception problems, despite normal pure-tone hearing and language ability. (2) When comparing the SCO and NSCM results, our findings are consistent with a reduced ability to label CV/VC sounds presented in random temporal order. This seems consistent with phone memory dysfunction. (3) These conclusions are at odds with previous studies finding no indication of phone identification impairment.

Problems of Speech Perception Experienced by the EFL Learners

Most native speakers of English modify complicated sequences in connected speech in order to simplify the articulation process. This habit has created problems in the part of EFL learners as they are not trained enough to extract word sequences from the running speech. As a consequence, misperception occurs, which often leads to the failure in the listening comprehension. This article is intended to prove that such a problem is not solely triggered by the native speaker factor. Other factors might play pivotal roles, too and need to be carefully examined. In light of this interest, a secondary research aimed at revealing factors causing speech perception problems was carried out. The research result shows that problems of speech perceptions experienced by the EFL learners were mostly caused by their phonetic knowledge and phonological competence, besides lexical and syntax knowledge.

Masked speech perception across the adult lifespan: Impact of age and hearing impairment

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.

A data-driven solution to the invariance problem in speech perception

A fundamental and unanswered question of speech perception is the ability of a listener to map the highly variable acoustic features of phones to perceptual categories such as phonemes. Several solutions to this problem have been proposed, which include the motor theory, direct realist, distinctive features, and exemplar models. In parallel, the same problem has been studied extensively in algorithmic emulation of speech perception, where the first step is to estimate phonemic categories from the acoustic signal. The recent breakthroughs in machine learning methods, particularly models inspired by neural circuits, have resulted in nearly human-level performance. However, the strategy exploited by the models in these data-driven approaches remains elusive. Here, we analyzed a deep neural network model trained to perform the acoustic-to-phoneme transformation and determined the representational and computational properties of the network as it forms categorical distinctions. We found that the network intern...

Aging Affects Neural Synchronization to Speech-Related Acoustic Modulations

As people age, speech perception problems become highly prevalent, especially in noisy situations. In addition to peripheral hearing and cognition, temporal processing plays a key role in speech perception. Temporal processing of speech features is mediated by synchronized activity of neural oscillations in the central auditory system. Previous studies indicate that both the degree and hemispheric lateralization of synchronized neural activity relate to speech perception performance. Based on these results, we hypothesize that impaired speech perception in older persons may, in part, originate from deviances in neural synchronization. In this study, auditory steady-state responses that reflect synchronized activity of theta, beta, low and high gamma oscillations (i.e., 4, 20, 40, and 80 Hz ASSR, respectively) were recorded in young, middle-aged, and older persons. As all participants had normal audiometric thresholds and were screened for (mild) cognitive impairment, differences in synchronized neural activity across the three age groups were likely to be attributed to age. Our data yield novel findings regarding theta and high gamma oscillations in the aging auditory system. At an older age, synchronized activity of theta oscillations is increased, whereas high gamma synchronization is decreased. In contrast to young persons who exhibit a right hemispheric dominance for processing of high gamma range modulations, older adults show a symmetrical processing pattern. These age-related changes in neural synchronization may very well underlie the speech perception problems in aging persons.

Effect of tinnitus location on the psychoacoustic measures of hearing

Objective: The present study was designed to assess psychoacoustic abilities in individuals with the complaint of tinnitus, the emphasis being on the location of tinnitus in the head.Study design: Psychoacoustic abilities were measured with temporal processing tests using four common measures. Gap-in-noise and modulation function tests were used to measure temporal resolution ability; duration pattern and duration discrimination tests were used to assess temporal ordering and temporal discrimination skills, respectively; and finally a backwards masking test was employed to determine temporal masking abilities. A clinical research design using standard group comparison was used with a cohort of 76 normal hearing participants divided into three groups: one with no complaint of tinnitus (n = 38), a second with tinnitus localized to either one of the ears (n = 22), and a third with tinnitus localized to both ears (n = 16).Results: A comparison between the normal and tinnitus groups revealed poor temporal processing skills in individuals with tinnitus. Within the tinnitus group, a comparison between those with unilateral and bilateral tinnitus indicated poor performance of the participants with bilateral tinnitus for most of the tests. The individuals with unilateral tinnitus were also assessed for tinnitus ear effect and no statistically significant difference was observed.Conclusion: Temporal processing skills were affected in individuals with tinnitus and the severity was more in those with bilateral tinnitus. As persons with temporal processing disorders are at high risk of developing speech perception problems, the early investigation and timely management of tinnitus is essential.

How does prosody influence speech categorization?

A recent study (Kim & Cho, 2013, The Journal of the Acoustical Society of America) reported that the perception of a prosodic boundary leads to a shift in a stop-identification function in English, so that stops with a relatively long VOT are accepted as voiced if occurring after a major prosodic boundary. Even Korean learners of English showed such a shift. This shift would seem to result from compensation for post-boundary lengthening effects (or domain-initial strengthening) and thereby help to overcome the invariance problem in speech perception. In two experiments, we ask how this effect comes about. The first experiment tested whether a simple adjustment to a change in overall speaking rate would be sufficient to account for the shift. Results showed that while the global speaking-rate change modulates phonetic categorization in a similar way as a change in the prosodic boundary strength, the speaking-rate effect is not sufficient to explain the boundary effect. That is, there was a more robust shift in a stop identification function with localized slowing down of the final syllable due to an intonational phrase (IP) boundary than with global slowing down of speaking rate. The second experiment therefore investigated the contribution of an F0 cue to the observed perceptual shift and found that the presence or absence of the F0 cue did not mediate the effect of prosodic boundaries on phonetic categorization. This suggests that a perception shift in phonetic categorization stems primarily from the listeners’ adjustment to temporal variation, though its source is different from the speaking rate. The results are considered in terms of two possible accounts: one that takes both the boundary-induced and the speaking rate-induced effects as listeners’ adjustments to low-level temporal variation, and the other that separates them by taking the boundary-induced effects to arise with computation of higher-level prosodic structure, given that the source of the localized slowing down effect is a prosodic boundary.

Characterisation of a Collective of Children with Early Language Delay, 'Late Talkers'

By considering their general development, 2-year-old children with delayed speech development (late -talkers, LT) were examined and described with respect to linguistic competence and hearing. Initially, 50 monolingual German speaking LT (age: 23-28 months) were recruited. In addition to audiological tests (impedance testing, otoacoustic emissions, reaction audiometry), language development status test was performed (clinical impression during examination, expressive vocabulary: FRAKIS, receptive competence: SETK-2). After exclusion of 10 children with general retarded development (3 premature infants, 2 children with suspicion of autism and 2 children with infantile brain damage) 33 LTs with normal hearing were included. The expressive vocabulary (FRAKIS) of 82% of these 33 LTs were below the normal range. 39% showed deficits in language comprehension tests (SETK-2) although parental reports mentioned language comprehension problems in only 3 LT. No correlation was found between vocabulary (FRAKIS) and language comprehension (SETK-2). The clinical collective in this study showed severely affected children with a high percentage of other abnormalities and speech perception problems in many cases. Despite normal hearing, vocabulary and especially speech comprehension should also be tested. LT with language comprehension problems require early developmental psychological investigation in order to prevent language and general developmental limitations. Only in this way, remedial instruction adapted to the develop-mental level can be initiated.

Sensorineural hearing loss amplifies neural coding of envelope information in the central auditory system of chinchillas

People with sensorineural hearing loss often have substantial difficulty understanding speech under challenging listening conditions. Behavioral studies suggest that reduced sensitivity to the temporal structure of sound may be responsible, but underlying neurophysiological pathologies are incompletely understood. Here, we investigate the effects of noise-induced hearing loss on coding of envelope (ENV) structure in the central auditory system of anesthetized chinchillas. ENV coding was evaluated noninvasively using auditory evoked potentials recorded from the scalp surface in response to sinusoidally amplitude modulated tones with carrier frequencies of 1, 2, 4, and 8 kHz and a modulation frequency of 140 Hz. Stimuli were presented in quiet and in three levels of white background noise. The latency of scalp-recorded ENV responses was consistent with generation in the auditory midbrain. Hearing loss amplified neural coding of ENV at carrier frequencies of 2 kHz and above. This result may reflect enhanced ENV coding from the periphery and/or an increase in the gain of central auditory neurons. In contrast to expectations, hearing loss was not associated with a stronger adverse effect of increasing masker intensity on ENV coding. The exaggerated neural representation of ENV information shown here at the level of the auditory midbrain helps to explain previous findings of enhanced sensitivity to amplitude modulation in people with hearing loss under some conditions. Furthermore, amplified ENV coding may potentially contribute to speech perception problems in people with cochlear hearing loss by acting as a distraction from more salient acoustic cues, particularly in fluctuating backgrounds.

Auditory Training: Evidence for Neural Plasticity in Older Adults.

Improvements in digital amplification, cochlear implants, and other innovations have extended the potential for improving hearing function; yet, there remains a need for further hearing improvement in challenging listening situations, such as when trying to understand speech in noise or when listening to music. Here, we review evidence from animal and human models of plasticity in the brain's ability to process speech and other meaningful stimuli. We considered studies targeting populations of younger through older adults, emphasizing studies that have employed randomized controlled designs and have made connections between neural and behavioral changes. Overall results indicate that the brain remains malleable through older adulthood, provided that treatment algorithms have been modified to allow for changes in learning with age. Improvements in speech-in-noise perception and cognition function accompany neural changes in auditory processing. The training-related improvements noted across studies support the need to consider auditory training strategies in the management of individuals who express concerns about hearing in difficult listening situations. Given evidence from studies engaging the brain's reward centers, future research should consider how these centers can be naturally activated during training.

Age-Related Changes in Cognition and Speech Perception

Aging is one of the most evident biological processes, but its mechanisms are still poorly understood. Studies of cognitive aging suggest that age is associated with cognitive decline; however, there may be individual differences such that not all older adults will experience cognitive decline. That is, cognitive decline is not intrinsic to aging, but there is some heterogeneity. Many researchers have shown that speech recognition declines with increasing age. Some of the age-related decline in speech perception can be accounted for by peripheral sensory problems but cognitive aging can also be a contributing factor. The potential sources of reduced recognition for rapid speech in the aged are reduction in processing time and reduction of the acoustic information in the signal. However, other studies also indicated that speech perception does not decline with age. Cognitive abilities are inherently involved in speech processing. Two cognitive factors that decline with age may influence speech perception performance. The first factor is working memory capacity and the second factor concerns the rate of information processing, defined generally as the speed at which an individual can extract content and construct meaning from a rapid signal. Cognitive function shows the adaptive processes with age which are consistent with the view that the brain itself has potentially a life-long capacity for neural plasticity. Assessing the speech perception difficulty in older adults, cognitive function could be considered in the evaluation and management of speech perception problem.

Speech perception in noise: Exploring the effect of linguistic context in children with and without auditory processing disorder

Objective: The objective of this study was to investigate whether the speech perception problems in noise of children with auditory processing disorder (APD) stem from an auditory or a higher order dysfunction. Design: A repeated measures design comparing the sentence key word recognition scores of children with APD and a control group was used. Four sentence lists from the Test de phrases dans le bruit (TPB) were presented with a babble masker at four different signal-to-noise ratios. The TPB is a Canadian French adaptation of the speech perception in noise test. Study Sample: Ten participants between 9–12 years with APD participated in this study, as well as ten age- and gender-matched children with no sign of APD. Results: Group analyses revealed that children with APD had poorer overall sentence key word recognition scores than the control group. Analysis of the difference scores between the high and low predictability sentences indicated that the benefit derived from linguistic context is similar between the groups. However, individual patterns of results revealed different profiles within the APD group. Conclusion: Further study using a larger sample is warranted to deepen our understanding of the nature of APD and identify characteristic profiles to enable better tailoring of therapeutic programs.SumarioObjetivo: El objetivo de este estudio fue investigar cuándo los problemas de percepción del habla en ruido, en niños con trastornos del procesamiento auditivo (APD), son producto de una disfunción auditiva o de niveles superiores. Diseño: Repetición de mediciones para comparar las puntuaciones de reconocimiento de palabras clave en una oración, entre niños con APD y los de un grupo control. Estudio: Se presentaron cuatro listas de oraciones del Test de Phrases dans le Bruit (TPB – Prueba de frases en ruido-) en presencia de balbuceo enmascarante, a cuatro diferentes relaciones señal/ruido. El TPB es una adaptación al Francés del Canadá, de la prueba de Percepción del Habla en Ruido. Muestra: Participaron en este estudio diez niños con APD entre 9-12 años y 10 niños sin signos de APD, pareados por edad y sexo. Resultados: El análisis de grupos reveló que los niños con APD tienen puntuaciones generales más pobres en el reconocimiento de palabras clave en oraciones, que los del grupo control. El análisis de las diferencias entre las puntuaciones de las oraciones de mayor o menor predictabilidad, indicaron que el beneficio que se deriva del contexto lingüístico es similar entre los dos grupos. Sin embargo, los patrones de resultados individuales, revelan diferentes perfiles en el grupo de niños con APD. Conclusiones: Se justifican estudios adicionales usando una muestra más amplia, para profundizar nuestro conocimiento sobre la naturaleza de los APD y para identificar perfiles característicos que nos permitan la mejor individualización de programas terapéuticos.

Reading fluency and speech perception speed of beginning readers with persistent reading problems: the perception of initial stop consonants and consonant clusters

This study investigated the role of speech perception accuracy and speed in fluent word decoding of reading disabled (RD) children. A same-different phoneme discrimination task with natural speech tested the perception of single consonants and consonant clusters by young but persistent RD children. RD children were slower than chronological age (CA) controls in recognizing identical sounds, suggesting less distinct phonemic categories. In addition, after controlling for phonetic similarity Tallal’s (Brain Lang 9:182–198, 1980) fast transitions account of RD children’s speech perception problems was contrasted with Studdert-Kennedy’s (Read Writ Interdiscip J 15:5–14, 2002) similarity explanation. Results showed no specific RD deficit in perceiving fast transitions. Both phonetic similarity and fast transitions influenced accurate speech perception for RD children as well as CA controls.

Auditory Processing Disorder and Speech Perception Problems in Noise: Finding the Underlying Origin

A hallmark listening problem of individuals presenting with auditory processing disorder (APD) is their poor recognition of speech in noise. The underlying perceptual problem of the listening difficulties in unfavorable listening conditions is unknown. The objective of this article was to demonstrate theoretically how to determine whether the speech recognition problems are related to an auditory dysfunction, a language-based dysfunction, or a combination of both. Tests such as the Speech Perception in Noise (SPIN) test allow the exploration of the auditory and language-based functions involved in speech perception in noise, which is not possible with most other speech-in-noise tests. Psychometric functions illustrating results from hypothetical groups of individuals with APD on the SPIN test are presented. This approach makes it possible to postulate about the origin of the speech perception problems in noise. APD is a complex and heterogeneous disorder for which the underlying deficit is currently unclear. Because of their design, SPIN-like tests can potentially be used to identify the nature of the deficits underlying problems with speech perception in noise for this population. A better understanding of the difficulties with speech perception in noise experienced by many listeners with APD should lead to more efficient intervention programs.

Transcriptional Regulation of Cortical Interneuron Development: Figure 1.

People with cochlear hearing loss have substantial difficulty understanding speech in real-world listening environments (e.g., restaurants), even with amplification from a modern digital hearing aid. Unfortunately, a disconnect remains between human perceptual studies implicating diminished sensitivity to fast acoustic temporal fine structure (TFS) and animal studies showing minimal changes in neural coding of TFS or slower envelope (ENV) structure. Here, we used general system-identification (Wiener kernel) analyses of chinchilla auditory nerve fiber responses to Gaussian noise to reveal pronounced distortions in tonotopic coding of TFS and ENV following permanent, noise-induced hearing loss. In basal fibers with characteristic frequencies (CFs) &gt;1.5 kHz, hearing loss introduced robust nontonotopic coding (i.e., at the wrong cochlear place) of low-frequency TFS, while ENV responses typically remained at CF. As a consequence, the highest dominant frequency of TFS coding in response to Gaussian noise was 2.4 kHz in noise-overexposed fibers compared with 4.5 kHz in control fibers. Coding of ENV also became nontonotopic in more pronounced cases of cochlear damage. In apical fibers, more classical hearing-loss effects were observed, i.e., broadened tuning without a significant shift in best frequency. Because these distortions and dissociations of TFS/ENV disrupt tonotopicity, a fundamental principle of auditory processing necessary for robust signal coding in background noise, these results have important implications for understanding communication difficulties faced by people with hearing loss. Further, hearing aids may benefit from distinct amplification strategies for apical and basal cochlear regions to address fundamentally different coding deficits. <b>SIGNIFICANCE STATEMENT</b> Speech-perception problems associated with noise overexposure are pervasive in today9s society, even with modern digital hearing aids. Unfortunately, the underlying physiological deficits in neural coding remain unclear. Here, we used innovative system-identification analyses of auditory nerve fiber responses to Gaussian noise to uncover pronounced distortions in coding of rapidly varying acoustic temporal fine structure and slower envelope cues following noise trauma. Because these distortions degrade and diminish the tonotopic representation of temporal acoustic features, a fundamental principle of auditory processing, the results represent a critical advancement in our understanding of the physiological bases of communication disorders. The detailed knowledge provided by this work will help guide the design of signal-processing strategies aimed at alleviating everyday communication problems for people with hearing loss.

Auditory processing, speech perception and phonological ability in pre-school children at high-risk for dyslexia: A longitudinal study of the auditory temporal processing theory

This study investigates whether the core bottleneck of literacy-impairment should be situated at the phonological level or at a more basic sensory level, as postulated by supporters of the auditory temporal processing theory. Phonological ability, speech perception and low-level auditory processing were assessed in a group of 5-year-old pre-school children at high-family risk for dyslexia, compared to a group of well-matched low-risk control children. Based on family risk status and first grade literacy achievement children were categorized in groups and pre-school data were retrospectively reanalyzed. On average, children showing both increased family risk and literacy-impairment at the end of first grade, presented significant pre-school deficits in phonological awareness, rapid automatized naming, speech-in-noise perception and frequency modulation detection. The concurrent presence of these deficits before receiving any formal reading instruction, might suggest a causal relation with problematic literacy development. However, a closer inspection of the individual data indicates that the core of the literacy problem is situated at the level of higher-order phonological processing. Although auditory and speech perception problems are relatively over-represented in literacy-impaired subjects and might possibly aggravate the phonological and literacy problem, it is unlikely that they would be at the basis of these problems. At a neurobiological level, results are interpreted as evidence for dysfunctional processing along the auditory-to-articulation stream that is implied in phonological processing, in combination with a relatively intact or inconsistently impaired functioning of the auditory-to-meaning stream that subserves auditory processing and speech perception.