Training to improve hearing speech in noise: biological mechanisms

Speech-in-Noise and Dichotic Auditory Training Students With Autism Spectrum Disorder

PURPOSE

Individuals diagnosed with autism spectrum disorder (ASD) often exhibit auditory processing issues, including poor speech recognition in background noise and dichotic processing (integration of different stimuli presented to the two ears). Auditory training could mitigate these auditory difficulties. However, few auditory training programs have been designed to target specific listening deficits for students with ASD. The present study summarizes the development of an innovative, one-on-one, clinician-developed speech-in-noise (SIN) training program that has not been previously described and an existing dichotic auditory training program to address common auditory processing deficits in students with ASD.

METHOD

Twenty verbal students with ASD, ages 7-17 years, completed a one-on-one, clinician-developed SIN training program and a commercially available dichotic training program 2-3 times a week (30-45 min per session) for 12 weeks. Maximum and minimum training levels from the SIN and dichotic training programs were analyzed statistically to document changes in training level over the training period.

RESULTS

Analyses of the pre- and posttraining data revealed significant improvements in training level for both the SIN and dichotic training programs.

CONCLUSIONS

Overall, the proposed SIN training resulted in significant improvements in training level and may be used along with dichotic training to improve some of the most common auditory processing issues documented in verbal individuals with ASD requiring minimal support. Both types of auditory training may be implemented in one-on-one therapy in clinics and in the schools.

Neural Delays in Processing Speech in Background Noise Minimized after Short-Term Auditory Training

Background noise disrupts the neural processing of sound, resulting in delayed and diminished far-field auditory-evoked responses. In young adults, we previously provided evidence that cognitively based short-term auditory training can ameliorate the impact of background noise on the frequency-following response (FFR), leading to greater neural synchrony to the speech fundamental frequency(F0) in noisy listening conditions. In this same dataset (55 healthy young adults), we now examine whether training-related changes extend to the latency of the FFR, with the prediction of faster neural timing after training. FFRs were measured on two days separated by ~8 weeks. FFRs were elicited by the syllable "da" presented at a signal-to-noise ratio (SNR) of +10 dB SPL relative to a background of multi-talker noise. Half of the participants participated in 20 sessions of computerized training (Listening and Communication Enhancement Program, LACE) between test sessions, while the other half served as Controls. In both groups, half of the participants were non-native speakers of English. In the Control Group, response latencies were unchanged at retest, but for the training group, response latencies were earlier. Findings suggest that auditory training can improve how the adult nervous system responds in noisy listening conditions, as demonstrated by decreased response latencies.

Preliminary Study on Speech in Noise Training in Children with Sensory Processing Disorder and Hyperacusis

Hyperacusis is the perception of certain everyday sounds as too loud or painful. Past research suggests that some individuals with Sensory Processing Disorder (SPD) may also have a comorbid hyperacusis. The aim of this preliminary study was to explore if hyperacusis symptoms in children with SPD change following Speech in noise training (SPINT). This was a retrospective cross-sectional study. Data were included for 28 children with SPD and sound intolerance (12/28 were female, mean age was 8.7 ± 1.9 years old). Patients were assessed using the Persian Buffalo Model Questionnaire-Revised version (P-BMQ-R) that measures various behavioural aspects of auditory processing disorder and word in noise test (WINT) before and after SPINT. After SPINT the subscales of DEC, TFM with its Noi, and Mem, subcategories, APD, ΣCAP, and Gen of P-BMQ-R questionnaire significantly improved (P < 0.05), however, the changes in subscales of Var, INT and ORG were not statistically significant (P > 0.05). In addition, SPINT led to better performance in WINT in both ears (P < 0.05). This preliminary study showed promising result for the effect of SPINT on improving behavioural indicators of APD (as measured via P-BMQ-R and WINT) and decreasing hyperacusis symptoms (as measured via Noi).

The Effect of Computer-Based Auditory Training on Speech-in-Noise Perception in Adults: a Systematic Review and Meta-Analysis

To investigate the effectiveness of computer-based auditory training on speech-in-noise perception in adults. With no language restriction, 11 databases were searched from 1990 to 2020. We included any clinical trial studies with concurrent comparison groups that examined the effectiveness of computer-based auditory training programs in adults. The primary outcome was a speech in noise perception that was estimated using the "difference pretest-posttest-control" index (dppc2). The risk of bias was assessed using the Cochrane collaboration tool for assessing the risk of bias in randomized trials. The certainty of the evidence was investigated using the GRADE in two primary outcomes. Twenty three studies were included in two subgroups based on primary outcome: 12 studies with speech perception threshold and 11 studies with speech-in-noise test scores. Computer-based auditory training resulted in a speech in noise perception improvement (dppc2:  -0.69, 95%CI:  -1.11 to  -0.26; I2 = 69.6%, p = 0.00) and (dppc2: 0.71, 95%CI: 0.38-1.03, I2: 17.8%, p = 0.27) respectively in both subgroups. 19 studies were judged to have a high risk of bias and 3 studies had a low risk of bias and the strength of the evidence was low in both primary outcomes. This finding indicates that computer-based auditory training can be a moderately effective intervention for speech-in-noise perception in adults. However, due to the low quality of primary studies and the low certainty of the evidence, the results are not yet definite. Prospero registration number: CRD42021233193.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12070-023-03920-0.

Effects of Auditory Training in Older Adults

PURPOSE

This study examines the effects of an auditory training program on the auditory and cognitive abilities of older adults. Auditory rehabilitation programs are generally designed for hearing aid users, and studies have demonstrated benefits for them. In this study, we seek to understand whether such a training program can also benefit older adults who do not wear hearing aids. We also examined if cognitive benefits can indeed be observed as a result of the training.

METHOD

Sixty-four older adults were recruited and assigned into three groups: the experimental group (n = 20), the active control group (n = 21), and the no-training control group (n = 23). The experimental group underwent an auditory training program (Listening and Communication Enhancement [LACE]) during the training phase. Meanwhile, the active control group listened to short audio clips and the no-training control group did not participate in any program. An auditory test (Quick Speech-in-Noise [QuickSIN]) and a battery of cognitive tests were conducted before and after the training to examine the participants' performance on auditory ability, short-term memory, and attention.

RESULTS

The results showed improvements in auditory and cognitive abilities during the training period. When assessing the training effects by comparing the pre- and the posttraining performances, a significant improvement on the QuickSIN task was found in the training group but not in the other two groups. However, other cognitive tests did not show any significant improvement. That is, the LACE training did not benefit short-term memory and attention. The improved performance on short-term memory during the training was not maintained in the posttraining session.

CONCLUSION

Overall, the study has extended the auditory benefit from the LACE training to the typical aging population in terms of improved communication ability, but the effect of training on auditory abilities did not transfer to gains in cognitive abilities.

Assessing the Development and Viability of an Android App for Auditory Training in Older Adults with Hearing Impairments

Purpose: This study aims to develop an android application that is more compatible and user-friendly for the older adult population with hearing impairment and validate the developed app. Method: The app's framework involved a training mode platform consisting of four levels with four sub-levels each. Every level includes stimuli of word-in-noise containing high and low-frequency words with three different noise types - traffic noise, competing for speech, and speech babble. The levels in the app increased in complexity to provide an efficient auditory training feature. The developed application was validated on older adults and professionals based on a questionnaire with both closed and open-ended questions. Results: Based on the validated responses of the participants, the app is a reliable tool for auditory training in older adults with hearing impairment. The app contains ease-of-use features for older adults and has been considered a platform for improvement in aural rehabilitation. Conclusion: The study marks as a tool in auditory training for older adults to provide the utmost benefit. Increase in the cases of the hearing-impaired population in a few years, a demand to set up a user-friendly management option is beneficiDigitizationtion of aural rehabilitation, especially for older adults, has thus been noted in the present study.

Central Auditory Processing Dysfunction in Service Members and Veterans: Treatment Considerations and Strategies

PURPOSE

Military risk factors such as blast exposure, noise exposure, head trauma, and neurotoxin exposure place Service members and Veterans at risk for deficits associated with auditory processing dysfunction. However, there is no clinical guidance specific to the treatment of auditory processing deficits in this unique population. We provide an overview of available treatments and their limited supporting evidence for use in adults, emphasizing the need for multidisciplinary case management and interdisciplinary research to support evidence-based solutions.

METHOD

We explored relevant literature to inform the treatment of auditory processing dysfunction in adults, with emphasis on findings involving active or former military personnel. We were able to identify a limited number of studies, pertaining primarily to the treatment of auditory processing deficits through the use of assistive technologies and training strategies. We assessed the current state of the science for knowledge gaps that warrant additional study.

CONCLUSIONS

Auditory processing deficits often co-occur with other military injuries and may pose significant risk in military operational and occupational settings. Research is needed to advance clinical diagnostic and rehabilitative capabilities, guide treatment planning, support effective multidisciplinary management, and inform fitness-for-duty standards. We emphasize the need for an inclusive approach to the assessment and treatment of auditory processing concerns in Service members and Veterans and for evidence-based solutions to address complex military risk factors and injuries.

Perceptual Learning of Noise-Vocoded Speech Under Divided Attention

Speech perception performance for degraded speech can improve with practice or exposure. Such perceptual learning is thought to be reliant on attention and theoretical accounts like the predictive coding framework suggest a key role for attention in supporting learning. However, it is unclear whether speech perceptual learning requires undivided attention. We evaluated the role of divided attention in speech perceptual learning in two online experiments (N = 336). Experiment 1 tested the reliance of perceptual learning on undivided attention. Participants completed a speech recognition task where they repeated forty noise-vocoded sentences in a between-group design. Participants performed the speech task alone or concurrently with a domain-general visual task (dual task) at one of three difficulty levels. We observed perceptual learning under divided attention for all four groups, moderated by dual-task difficulty. Listeners in easy and intermediate visual conditions improved as much as the single-task group. Those who completed the most challenging visual task showed faster learning and achieved similar ending performance compared to the single-task group. Experiment 2 tested whether learning relies on domain-specific or domain-general processes. Participants completed a single speech task or performed this task together with a dual task aiming to recruit domain-specific (lexical or phonological), or domain-general (visual) processes. All secondary task conditions produced patterns and amount of learning comparable to the single speech task. Our results demonstrate that the impact of divided attention on perceptual learning is not strictly dependent on domain-general or domain-specific processes and speech perceptual learning persists under divided attention.

Subcortical and Cortical Electrophysiological Measures in Children With Speech-in-Noise Deficits Associated With Auditory Processing Disorders

PURPOSE

The aim of this study was to analyze the subcortical and cortical auditory evoked potentials for speech stimuli in children with speech-in-noise (SIN) deficits associated with auditory processing disorder (APD) without any reading or language deficits.

METHOD

The study included 20 children in the age range of 9-13 years. Ten children were recruited to the APD group; they had below-normal scores on the speech-perception-in-noise test and were diagnosed as having APD. The remaining 10 were typically developing (TD) children and were recruited to the TD group. Speech-evoked subcortical (brainstem) and cortical (auditory late latency) responses were recorded and compared across both groups.

RESULTS

The results showed a statistically significant reduction in the amplitudes of the subcortical potentials (both for stimulus in quiet and in noise) and the magnitudes of the spectral components (fundamental frequency and the second formant) in children with SIN deficits in the APD group compared to the TD group. In addition, the APD group displayed enhanced amplitudes of the cortical potentials compared to the TD group.

CONCLUSION

Children with SIN deficits associated with APD exhibited impaired coding/processing of the auditory information at the level of the brainstem and the auditory cortex.

SUPPLEMENTAL MATERIAL

https://doi.org/10.23641/asha.21357735.

Evidence for a Musician Speech-Perception-in-Noise Advantage in School-Age Children

PURPOSE

The objective of this study was to evaluate whether child musicians are better at listening to speech in noise (SPIN) than nonmusicians of the same age. In addition, we aimed to explore whether the musician SPIN advantage in children was related to general intelligence (IQ).

METHOD

Fifty-one children aged 8.2-11.8 years and with different levels of music training participated in the study. A between-group design and correlational analyses were used to determine differences in SPIN skills as they relate to music training. IQ was used as a covariate to explore the relationship between intelligence and SPIN ability.

RESULTS

More years of music training were associated with better SPIN skills than fewer years of music training. Furthermore, this difference in SPIN skills remained even when accounting for IQ. These results were found at the group level and also when years of instrument training was treated as a continuous variable (i.e., correlational analyses).

CONCLUSIONS

We confirmed results from previous studies in which child musicians outperformed nonmusicians in SPIN skills. We also showed that this effect was not related to differences in IQ between the musicians and nonmusicians for this cohort of children. However, confirmation of this finding with a cohort of children from more diverse socioeconomic statuses and cognitive profiles is warranted.

Event-Related Potential Evidence for Involuntary Consciousness During Implicit Memory Retrieval

Classical notion claims that a memory is implicit if has nothing to do with consciousness during the information retrieval from storage, or is otherwise explicit. Here, we demonstrate event-related potential evidence for involuntary consciousness during implicit memory retrieval. We designed a passive oddball paradigm for retrieval of implicit memory in which an auditory stream of Shepard tones with musical pitch interval contrasts were delivered to the subjects. These contrasts evoked a mismatch negativity response, which is an event-related potential and a neural marker of implicit memory, in the subjects with long-term musical training, but not in the subjects without. Notably, this response was followed by a salient P3 component which implies involvement of involuntary consciousness in the implicit memory retrieval. Finally, source analysis of the P3 revealed moving dipoles from the frontal lobe to the insula, a brain region closely related to conscious attention. Our study presents a case of involvement of involuntary consciousness in the implicit memory retrieval and suggests a potential challenge to the classical definition of implicit memory.

Rapid but specific perceptual learning partially explains individual differences in the recognition of challenging speech

Perceptual learning for speech, defined as long-lasting changes in speech recognition following exposure or practice occurs under many challenging listening conditions. However, this learning is also highly specific to the conditions in which it occurred, such that its function in adult speech recognition is not clear. We used a time-compressed speech task to assess learning following either brief exposure (rapid learning) or additional training (training-induced learning). Both types of learning were robust and long-lasting. Individual differences in rapid learning explained unique variance in recognizing natural-fast speech and speech-in-noise with no additional contribution for training-induced learning (Experiment 1). Rapid learning was stimulus specific (Experiment 2), as in previous studies on training-induced learning. We suggest that rapid learning is key for understanding the role of perceptual learning in online speech recognition whereas longer training could provide additional opportunities to consolidate and stabilize learning.

Hearing Therapy Improves Tinnitus-Related Distress in Mildly Distressed Patients with Chronic Tinnitus and Mild-to-Moderate Hearing Loss: A Randomized-Controlled Cross-Over Design

BACKGROUND

The psychological effects of hearing aids and auditory training are underinvestigated.

OBJECTIVE

To assess the short- and long-term effects of an industry-developed auditory training on tinnitus-related distress, perceived stress, and psychological epiphenomena in patients with chronic tinnitus and mild-to-moderate hearing loss.

METHOD

One-hundred-seventy-seven gender-stratified patients were randomized to an immediate [IIG] or delayed [DIG] intervention group. Following binaural hearing aid fitting, participants completed a CD-enhanced 14-days self-study program. Applying a randomized-controlled cross-over design, psychological measures were obtained at four times: pre-treatment/wait [IIG: t₁; DIG: wait], post-treatment/pre-treatment [IIG: t₂; DIG: t₁], follow-up/post-treatment [IIG: t₃; DIG: t₂], and follow-up [DIG: t₃]. Between- and within-group analyses investigated treatment-related effects and their stability at a 70-day follow-up.

RESULTS

Overall, distress symptom severity was mild. Unlike the DIG, the IIG showed significant improvements in tinnitus-related distress. Some psychological epiphenomena, notably anxiety, slightly improved in both groups. Within-group analyses demonstrated the stability of the tinnitus-distress-related effects, alongside uncontrolled improvements of perceived stress and mood-related symptoms at follow-up.

CONCLUSIONS

The investigated hearing therapy lastingly improves tinnitus-related distress in mildly distressed patients with chronic tinnitus and mild-to-moderate hearing loss. Beneficial psychological knock-on effects deserve further investigation.

Auditory training for adults with cochlear implants: a systematic review

OBJECTIVE

To systematically review the peer-reviewed literature on the efficacy of auditory training (AT) on auditory outcomes in post lingually deafened adults with cochlear implants (CIs).

DESIGN

A systematic review.

STUDY SAMPLE

Searches of five electronic databases yielded 10 studies published after 2010 that met the inclusion criteria.

RESULTS

For post lingually deafened adults with CIs, the evidence is suggestive that some AT can improve some auditory outcomes compared to no training. More specifically, the evidence suggests that phonemic training can improve identification of trained phonemes, and nonsense word training can improve sentence recognition in noise in this population.

CONCLUSIONS

While many AT interventions are currently being used with post lingually deafened adults with CIs, the evidence for AT improving auditory outcomes is suggestive with the best evidence being for nonsense word training improving sentence recognition in noise by an average of 10% with these improvements retained at 26 weeks post-training in this population. There remains a need for high quality studies that have the capacity to demonstrate, clearly and unequivocally, which AT is most effective for improving which auditory outcomes in this population.

Rapid Enhancement of Subcortical Neural Responses to Sine-Wave Speech

The efferent auditory nervous system may be a potent force in shaping how the brain responds to behaviorally significant sounds. Previous human experiments using the frequency following response (FFR) have shown efferent-induced modulation of subcortical auditory function online and over short- and long-term time scales; however, a contemporary understanding of FFR generation presents new questions about whether previous effects were constrained solely to the auditory subcortex. The present experiment used sine-wave speech (SWS), an acoustically-sparse stimulus in which dynamic pure tones represent speech formant contours, to evoke FFR_SWS. Due to the higher stimulus frequencies used in SWS, this approach biased neural responses toward brainstem generators and allowed for three stimuli (/bɔ/, /bu/, and /bo/) to be used to evoke FFR_SWSbefore and after listeners in a training group were made aware that they were hearing a degraded speech stimulus. All SWS stimuli were rapidly perceived as speech when presented with a SWS carrier phrase, and average token identification reached ceiling performance during a perceptual training phase. Compared to a control group which remained naïve throughout the experiment, training group FFR_SWS amplitudes were enhanced post-training for each stimulus. Further, linear support vector machine classification of training group FFR_SWS significantly improved post-training compared to the control group, indicating that training-induced neural enhancements were sufficient to bolster machine learning classification accuracy. These results suggest that the efferent auditory system may rapidly modulate auditory brainstem representation of sounds depending on their context and perception as non-speech or speech.

Deficient neural encoding of speech sounds in term neonates born after fetal growth restriction

Infants born after fetal growth restriction (FGR)-an obstetric condition defined as the failure to achieve the genetic growth potential-are prone to neurodevelopmental delays, with language being one of the major affected areas. Yet, while verbal comprehension and expressive language impairments have been observed in FGR infants, children and even adults, specific related impairments at birth, such as in the ability to encode the sounds of speech, necessary for language acquisition, remain to be disclosed. Here, we used the frequency-following response (FFR), a brain potential correlate of the neural phase locking to complex auditory stimuli, to explore the encoding of speech sounds in FGR neonates. Fifty-three neonates born with FGR and 48 controls born with weight adequate-for-gestational age (AGA) were recruited. The FFR was recorded to the consonant-vowel stimulus (/da/) during sleep and quantified as the spectral amplitude to the fundamental frequency of the syllable and its signal-to-noise ratio (SNR). The outcome was available in 45 AGA and 51 FGR neonates, yielding no differences for spectral amplitudes. However, SNR was strongly attenuated in the FGR group compared to the AGA group at the vowel region of the stimulus. These findings suggest that FGR population present a deficit in the neural pitch tracking of speech sounds already present at birth. Our results pave the way for future research on the potential clinical use of the FFR in this population, so that if confirmed, a disrupted FFR recorded at birth may help deriving FGR neonates at risk for postnatal follow-ups.

Auditory Cortical Changes Precede Brainstem Changes During Rapid Implicit Learning: Evidence From Human EEG

The auditory system is sensitive to stimulus regularities such as frequently occurring sounds and sound combinations. Evidence of regularity detection can be seen in how neurons across the auditory network, from brainstem to cortex, respond to the statistical properties of the soundscape, and in the rapid learning of recurring patterns in their environment by children and adults. Although rapid auditory learning is presumed to involve functional changes to the auditory network, the chronology and directionality of changes are not well understood. To study the mechanisms by which this learning occurs, auditory brainstem and cortical activity was simultaneously recorded via electroencephalogram (EEG) while young adults listened to novel sound streams containing recurring patterns. Neurophysiological responses were compared between easier and harder learning conditions. Collectively, the behavioral and neurophysiological findings suggest that cortical and subcortical structures each provide distinct contributions to auditory pattern learning, but that cortical sensitivity to stimulus patterns likely precedes subcortical sensitivity.

Improved Speech in Noise Perception in the Elderly After 6 Months of Musical Instruction

Understanding speech in background noise poses a challenge in daily communication, which is a particular problem among the elderly. Although musical expertise has often been suggested to be a contributor to speech intelligibility, the associations are mostly correlative. In the present multisite study conducted in Germany and Switzerland, 156 healthy, normal-hearing elderly were randomly assigned to either piano playing or music listening/musical culture groups. The speech reception threshold was assessed using the International Matrix Test before and after a 6 month intervention. Bayesian multilevel modeling revealed an improvement of both groups over time under binaural conditions. Additionally, the speech reception threshold of the piano group decreased during stimuli presentation to the left ear. A right ear improvement only occurred in the German piano group. Furthermore, improvements were predominantly found in women. These findings are discussed in the light of current neuroscientific theories on hemispheric lateralization and biological sex differences. The study indicates a positive transfer from musical training to speech processing, probably supported by the enhancement of auditory processing and improvement of general cognitive functions.

Auditory Cortical Plasticity Dependent on Environmental Noise Statistics

During critical periods, neural circuits develop to form receptive fields that adapt to the sensory environment and enable optimal performance of relevant tasks. We hypothesized that early exposure to background noise can improve signal-in-noise processing, and the resulting receptive field plasticity in the primary auditory cortex can reveal functional principles guiding that important task. We raised rat pups in different spectro-temporal noise statistics during their auditory critical period. As adults, they showed enhanced behavioral performance in detecting vocalizations in noise. Concomitantly, encoding of vocalizations in noise in the primary auditory cortex improves with noise-rearing. Significantly, spectro-temporal modulation plasticity shifts cortical preferences away from the exposed noise statistics, thus reducing noise interference with the foreground sound representation. Auditory cortical plasticity shapes receptive field preferences to optimally extract foreground information in noisy environments during noise-rearing. Early noise exposure induces cortical circuits to implement efficient coding in the joint spectral and temporal modulation domain.

After rearing rats in moderately loud spectro-temporally modulated background noise, Homma et al. investigated signal-in-noise processing in the primary auditory cortex. Noise-rearing improved vocalization-in-noise performance in both behavioral testing and neural decoding. Cortical plasticity shifted neuronal spectro-temporal modulation preferences away from the exposed noise statistics.

Improving older adults' understanding of challenging speech: Auditory training, rapid adaptation and perceptual learning

The literature surrounding auditory perceptual learning and auditory training for challenging speech signals in older adult listeners is highly varied, in terms of both study methodology and reported outcomes. In this review, we discuss some of the pertinent features of listener, stimulus, and training protocol. Literature regarding the elicitation of auditory perceptual learning for time-compressed speech, non-native speech, and noise-vocoded speech is reviewed, as are auditory training protocols designed to improve speech-in-noise recognition. The literature is synthesized to establish some over-arching findings for the aging population, including an intact capacity for auditory perceptual learning, but a limited transfer of learning to untrained stimuli.

Short-Term Pediatric Acclimatization to Adaptive Hearing Aid Technology

Purpose This exploratory study assessed the perceptual, cognitive, and academic learning effects of an adaptive, integrated, directionality, and noise reduction hearing aid program in pediatric users. Method Fifteen pediatric hearing aid users (6-12 years old) received new bilateral, individually fitted Oticon Opn hearing aids programmed with OpenSound Navigator (OSN) processing. Word recognition in noise, sentence repetition in quiet, nonword repetition, vocabulary learning, selective attention, executive function, memory, and reading and mathematical abilities were measured within 1 week of the initial hearing aid fitting and 2 months post fit. Caregivers completed questionnaires assessing their child's listening and communication abilities prior to study enrollment and after 2 months of using the study hearing aids. Results Caregiver reporting indicated significant improvements in speech and sound perception, spatial sound awareness, and the ability to participate in conversations. However, there was no positive change in performance in any of the measured skills. Mathematical scores significantly declined after 2 months. Conclusions OSN provided a perceived improvement in functional benefit, compared to their previous hearing aids, as reported by caregivers. However, there was no positive change in listening skills, cognition, and academic success after 2 months of using OSN. Findings may have been impacted by reporter bias, limited sample size, and a relatively short trial period. This study took place during the summer when participants were out of school, which may have influenced the decline in mathematical scores. The results support further exploration with age- and audiogram-matched controls, larger sample sizes, and longer test-retest intervals that correspond to the academic school year.

Experiences of Patients With Auditory Processing Disorder in Getting Support in Health, Education, and Work Settings: Findings From an Online Survey

Objective: To explore the views and experiences of individuals with Auditory Processing Disorder (APD) and/or their families in getting support from services and to receive their suggestions for improvement.

Design: Cross-sectional random sample survey with descriptive analysis.

Settings: Online survey.

Participants: One hundred and fifty six individuals with APD and/or their family members from the APD Support UK patient support organization and four associated APD Facebook groups.

Main Outcome Measure: A 16-item questionnaire on negative and positive experiences in getting a referral for diagnosis, funding for the FM system, and overall support for APD.

Results: The key findings that emerged included reports of difficulty in getting a referral for diagnosis (54%), obtaining funding for an FM system (45%), getting support for APD (61%), and poor recognition and awareness of APD (63%) in Education, Health or Work settings. The positive experiences reported were ease in getting a referral for diagnosis (46%), in obtaining an FM system (20%), and with diagnosis leading to help at school or to a better understanding of the condition and the required adjustments. The recommended improvement areas were raising awareness of APD and related management in Education (30%), the Health sector (25%), and the public (18%).

Conclusions: Individuals and families of individuals with APD overwhelmingly report a lack of awareness of APD across health, education, and work sectors, and difficulties in getting access to diagnosis and support. This information may provide an initial understanding of the patients' needs for clinical services for APD, identify research priorities, and influence longer-term public health decisions toward improved care.

Neural generators of the frequency-following response elicited to stimuli of low and high frequency: A magnetoencephalographic (MEG) study

The frequency-following response (FFR) to periodic complex sounds has gained recent interest in auditory cognitive neuroscience as it captures with great fidelity the tracking accuracy of the periodic sound features in the ascending auditory system. Seminal studies suggested the FFR as a correlate of subcortical sound encoding, yet recent studies aiming to locate its sources challenged this assumption, demonstrating that FFR receives some contribution from the auditory cortex. Based on frequency-specific phase-locking capabilities along the auditory hierarchy, we hypothesized that FFRs to higher frequencies would receive less cortical contribution than those to lower frequencies, hence supporting a major subcortical involvement for these high frequency sounds. Here, we used a magnetoencephalographic (MEG) approach to trace the neural sources of the FFR elicited in healthy adults (N = 19) to low (89 Hz) and high (333 Hz) frequency sounds. FFRs elicited to the high and low frequency sounds were clearly observable on MEG and comparable to those obtained in simultaneous electroencephalographic recordings. Distributed source modeling analyses revealed midbrain, thalamic, and cortical contributions to FFR, arranged in frequency-specific configurations. Our results showed that the main contribution to the high-frequency sound FFR originated in the inferior colliculus and the medial geniculate body of the thalamus, with no significant cortical contribution. In contrast, the low-frequency sound FFR had a major contribution located in the auditory cortices, and also received contributions originating in the midbrain and thalamic structures. These findings support the multiple generator hypothesis of the FFR and are relevant for our understanding of the neural encoding of sounds along the auditory hierarchy, suggesting a hierarchical organization of periodicity encoding.

Efferent unmasking of speech-in-noise encoding?

OBJECTIVE

The medial olivocochlear (MOC) reflex provides efferent feedback from the brainstem to cochlear outer hair cells. Physiologic studies have demonstrated that the MOC reflex is involved in "unmasking" of signals-in-noise at the level of the auditory nerve; however, its functional importance in human hearing remains unclear.

DESIGN

This study examined relationships between pre-neural measurements of MOC reflex strength (click-evoked otoacoustic emission inhibition; CEOAE) and neural measurements of speech-in-noise encoding (speech frequency following response; sFFR) in four conditions (Quiet, Contralateral Noise, Ipsilateral Noise, and Ipsilateral + Contralateral Noise). Three measures of CEOAE inhibition (amplitude reduction, effective attenuation, and input-output slope inhibition) were used to quantify pre-neural MOC reflex strength. Correlations between pre-neural MOC reflex strength and sFFR "unmasking" (i.e. response recovery from masking effects with activation of the MOC reflex in time and frequency domains) were assessed.

STUDY SAMPLE

18 young adults with normal hearing.

RESULTS

sFFR unmasking effects were insignificant, and there were no correlations between pre-neural MOC reflex strength and sFFR unmasking in the time or frequency domain.

CONCLUSION

Our results do not support the hypothesis that the MOC reflex is involved in speech-in-noise neural encoding, at least for features that are represented in the sFFR at the SNR tested.

Papesh M, Gallun FJ. A Questionnaire Survey of Current Rehabilitation Practices for Adults With Normal Hearing Sensitivity Who Experience Auditory Difficulties

Purpose A questionnaire survey was conducted to collect information from clinical audiologists about rehabilitation options for adult patients who report significant auditory difficulties despite having normal or near-normal hearing sensitivity. This work aimed to provide more information about what audiologists are currently doing in the clinic to manage auditory difficulties in this patient population and their views on the efficacy of recommended rehabilitation methods. Method A questionnaire survey containing multiple-choice and open-ended questions was developed and disseminated online. Invitations to participate were delivered via e-mail listservs and through business cards provided at annual audiology conferences. All responses were anonymous at the time of data collection. Results Responses were collected from 209 participants. The majority of participants reported seeing at least one normal-hearing patient per month who reported significant communication difficulties. However, few respondents indicated that their location had specific protocols for the treatment of these patients. Counseling was reported as the most frequent rehabilitation method, but results revealed that audiologists across various work settings are also successfully starting to fit patients with mild-gain hearing aids. Responses indicated that patient compliance with computer-based auditory training methods was regarded as low, with patients generally preferring device-based rehabilitation options. Conclusions Results from this questionnaire survey strongly suggest that audiologists frequently see normal-hearing patients who report auditory difficulties, but that few clinicians are equipped with established protocols for diagnosis and management. While many feel that mild-gain hearing aids provide considerable benefit for these patients, very little research has been conducted to date to support the use of hearing aids or other rehabilitation options for this unique patient population. This study reveals the critical need for additional research to establish evidence-based practice guidelines that will empower clinicians to provide a high level of clinical care and effective rehabilitation strategies to these patients.

Speech frequency-following response in human auditory cortex is more than a simple tracking

The human auditory cortex is recently found to contribute to the frequency following response (FFR) and the cortical component has been shown to be more relevant to speech perception. However, it is not clear how cortical FFR may contribute to the processing of speech fundamental frequency (F0) and the dynamic pitch. Using intracranial EEG recordings, we observed a significant FFR at the fundamental frequency (F0) for both speech and speech-like harmonic complex stimuli in the human auditory cortex, even in the missing fundamental condition. Both the spectral amplitude and phase coherence of the cortical FFR showed a significant harmonic preference, and attenuated from the primary auditory cortex to the surrounding associative auditory cortex. The phase coherence of the speech FFR was found significantly higher than that of the harmonic complex stimuli, especially in the left hemisphere, showing a high timing fidelity of the cortical FFR in tracking dynamic F0 in speech. Spectrally, the frequency band of the cortical FFR was largely overlapped with the range of the human vocal pitch. Taken together, our study parsed the intrinsic properties of the cortical FFR and reveals a preference for speech-like sounds, supporting its potential role in processing speech intonation and lexical tones.

An Automated Speech-in-Noise Test for Remote Testing: Development and Preliminary Evaluation

Purpose The aim of this study was to develop and evaluate a novel, automated speech-in-noise test viable for widespread in situ and remote screening. Method Vowel-consonant-vowel sounds in a multiple-choice consonant discrimination task were used. Recordings from a professional male native English speaker were used. A novel adaptive staircase procedure was developed, based on the estimated intelligibility of stimuli rather than on theoretical binomial models. Test performance was assessed in a population of 26 young adults (YAs) with normal hearing and in 72 unscreened adults (UAs), including native and nonnative English listeners. Results The proposed test provided accurate estimates of the speech recognition threshold (SRT) compared to a conventional adaptive procedure. Consistent outcomes were observed in YAs in test/retest and in controlled/uncontrolled conditions and in UAs in native and nonnative listeners. The SRT increased with increasing age, hearing loss, and self-reported hearing handicap in UAs. Test duration was similar in YAs and UAs irrespective of age and hearing loss. The test-retest repeatability of SRTs was high (Pearson correlation coefficient = .84), and the pass/fail outcomes of the test were reliable in repeated measures (Cohen's κ = .8). The test was accurate in identifying ears with pure-tone thresholds > 25 dB HL (accuracy = 0.82). Conclusion This study demonstrated the viability of the proposed test in subjects of varying language in terms of accuracy, reliability, and short test time. Further research is needed to validate the test in a larger population across a wider range of languages and hearing loss and to identify optimal classification criteria for screening purposes.

Listening in complex acoustic scenes

Being able to pick out particular sounds, such as speech, against a background of other sounds represents one of the key tasks performed by the auditory system. Understanding how this happens is important because speech recognition in noise is particularly challenging for older listeners and for people with hearing impairments. Central to this ability is the capacity of neurons to adapt to the statistics of sounds reaching the ears, which helps to generate noise-tolerant representations of sounds in the brain. In more complex auditory scenes, such as a cocktail party — where the background noise comprises other voices, sound features associated with each source have to be grouped together and segregated from those belonging to other sources. This depends on precise temporal coding and modulation of cortical response properties when attending to a particular speaker in a multi-talker environment. Furthermore, the neural processing underlying auditory scene analysis is shaped by experience over multiple timescales.

Speech-in-noise detection is related to auditory working memory precision for frequency

Speech-in-noise (SiN) perception is a critical aspect of natural listening, deficits in which are a major contributor to the hearing handicap in cochlear hearing loss. Studies suggest that SiN perception correlates with cognitive skills, particularly phonological working memory: the ability to hold and manipulate phonemes or words in mind. We consider here the idea that SiN perception is linked to a more general ability to hold sound objects in mind, auditory working memory, irrespective of whether the objects are speech sounds. This process might help combine foreground elements, like speech, over seconds to aid their separation from the background of an auditory scene. We investigated the relationship between auditory working memory precision and SiN thresholds in listeners with normal hearing. We used a novel paradigm that tests auditory working memory for non-speech sounds that vary in frequency and amplitude modulation (AM) rate. The paradigm yields measures of precision in frequency and AM domains, based on the distribution of participants’ estimates of the target. Across participants, frequency precision correlated significantly with SiN thresholds. Frequency precision also correlated with the number of years of musical training. Measures of phonological working memory did not correlate with SiN detection ability. Our results demonstrate a specific relationship between working memory for frequency and SiN. We suggest that working memory for frequency facilitates the identification and tracking of foreground objects like speech during natural listening. Working memory performance for frequency also correlated with years of musical instrument experience suggesting that the former is potentially modifiable.

Noise-Induced Changes of the Auditory Brainstem Response to Speech-a Measure of Neural Desynchronisation?

It is commonly assumed that difficulty in listening to speech in noise is at least partly due to deficits in neural temporal processing. Given that noise reduces the temporal fidelity of the auditory brainstem response (ABR) to speech, it has been suggested that the speech ABR may serve as an index of such neural deficits. However, the temporal fidelity of ABRs, to both speech and non-speech sounds, is also known to be influenced by the cochlear origin of the response, as responses from higher-frequency cochlear regions are faster and more synchronous than responses from lower-frequency regions. Thus, if noise caused a reweighting of response contributions from higher- to lower-frequency cochlear regions, the temporal fidelity of the aggregate response should be reduced even in the absence of any changes in neural processing. This ‘place mechanism’ has been demonstrated for non-speech ABRs. The aim of this study was to test whether it also applies to speech ABRs. We used the so-called ‘derived-band’ method to isolate response contributions from frequency-limited cochlear regions. Broadband and derived-band speech ABRs were measured both in quiet and in noise. Whilst the noise caused significant changes to the temporal properties of the broadband response, its effects on the derived-band responses were mostly restricted to the response amplitudes. Importantly, the amplitudes of the higher-frequency derived-band responses were much more strongly affected than those of the lower-frequency responses, suggesting that the noise indeed caused a reweighting effect. Our results indicate that, as for non-speech ABRs, the cochlear place mechanism can represent a potentially substantial confound to speech-ABR-in-noise measurements.

Cognitive mechanisms underpinning successful perception of different speech distortions

Few studies thus far have investigated whether perception of distorted speech is consistent across different types of distortion. This study investigated whether participants show a consistent perceptual profile across three speech distortions: time-compressed, noise-vocoded, and speech in noise. Additionally, this study investigated whether/how individual differences in performance on a battery of audiological and cognitive tasks links to perception. Eighty-eight participants completed a speeded sentence-verification task with increases in accuracy and reductions in response times used to indicate performance. Audiological and cognitive task measures include pure tone audiometry, speech recognition threshold, working memory, vocabulary knowledge, attention switching, and pattern analysis. Despite previous studies suggesting that temporal and spectral/environmental perception require different lexical or phonological mechanisms, this study shows significant positive correlations in accuracy and response time performance across all distortions. Results of a principal component analysis and multiple linear regressions suggest that a component based on vocabulary knowledge and working memory predicted performance in the speech in quiet, time-compressed and speech in noise conditions. These results suggest that listeners employ a similar cognitive strategy to perceive different temporal and spectral/environmental speech distortions and that this mechanism is supported by vocabulary knowledge and working memory.

Effects of stimulus repetition and training schedule on the perceptual learning of time-compressed speech and its transfer

Perceptual learning can facilitate the recognition of hard-to-perceive (e.g., time-compressed or spectrally-degraded) speech. Although the learning induced by training with time-compressed speech is robust, previous findings suggest that intensive training yields learning that is partially specific to the items encountered during practice. Here, we asked whether three parameters of the training procedure - the overall number of training trials (training intensity), how these trials are distributed across sessions, and the number of semantically different items encountered during training (set size) - influence learning and transfer. Different groups of participants (69 normal-hearing young adults; nine to 11 participants/group) completed different training protocols (or served as an untrained control group) and tested on the recognition of time-compressed sentences taken from the training set (learning), new time-compressed sentences presented by the trained talker (semantic transfer), and time-compressed sentences taken from the training set but presented by a different talker (acoustic transfer). Compared to untrained listeners, all training protocols yielded both learning and transfer. More intense training resulted in greater item-specific learning and greater acoustic transfer than less intense training with the same number of training sessions. Training on a smaller set size (i.e., greater token repetition during training) also resulted in greater acoustic transfer, whereas distributing practice over a number of sessions improved semantic transfer. Together, these data suggest that whereas practice on a small set that results in stimulus repetition during training is not harmful for learning, distributed training can support transfer to new stimuli, perhaps because it provides multiple opportunities to consolidate learning.

Short-Term Choir Singing Supports Speech-in-Noise Perception and Neural Pitch Strength in Older Adults With Age-Related Hearing Loss

Prior studies have demonstrated musicianship enhancements of various aspects of auditory and cognitive processing in older adults, but musical training has rarely been examined as an intervention for mitigating age-related declines in these abilities. The current study investigates whether 10 weeks of choir participation can improve aspects of auditory processing in older adults, particularly speech-in-noise (SIN) perception. A choir-singing group and an age- and audiometrically-matched do-nothing control group underwent pre- and post-testing over a 10-week period. Linear mixed effects modeling in a regression analysis showed that choir participants demonstrated improvements in speech-in-noise perception, pitch discrimination ability, and the strength of the neural representation of speech fundamental frequency. Choir participants' gains in SIN perception were mediated by improvements in pitch discrimination, which was in turn predicted by the strength of the neural representation of speech stimuli (FFR), suggesting improvements in pitch processing as a possible mechanism for this SIN perceptual improvement. These findings support the hypothesis that short-term choir participation is an effective intervention for mitigating age-related hearing losses.

Simultaneous EEG and MEG recordings reveal vocal pitch elicited cortical gamma oscillations in young and older adults

The frequency-following response with origin in the auditory brainstem represents the pitch contour of voice and can be recorded with electrodes from the scalp. MEG studies also revealed a cortical contribution to the high gamma oscillations at the fundamental frequency (f₀) of a vowel stimulus. Therefore, studying the cortical component of the frequency-following response could provide insights into how pitch information is encoded at the cortical level. Comparing how aging affects the different responses may help to uncover the neural mechanisms underlying speech understanding deficits in older age. We simultaneously recorded EEG and MEG responses to the syllable /ba/. MEG beamformer analysis localized sources in bilateral auditory cortices and the midbrain. Time-frequency analysis showed a faithful representation of the pitch contour between 106 Hz and 138 Hz in the cortical activity. A cross-correlation revealed a latency of 20 ms. Furthermore, stimulus onsets elicited cortical 40-Hz responses. Both the 40-Hz and the f₀ response amplitudes increased in older age and were larger in the right hemisphere. The effects of aging and laterality of the f₀ response were evident in the MEG only, suggesting that both effects were characteristics of the cortical response. After comparing f₀ and N1 responses in EEG and MEG, we estimated that approximately one-third of the scalp-recorded f₀ response could be cortical in origin. We attributed the significance of the cortical f₀ response to the precise timing of cortical neurons that serve as a time-sensitive code for pitch.

DEVELOPMENT AND VALIDATION OF A METHOD TO ENHANCE AUDITORY ATTENTION DURING CONTINUOUS SPEECH-SHAPED NOISE ENVIRONMENT

Auditory training (AT) may strengthen auditory skills that help human not only in on-task auditory perception performance but in continuous speech-shaped noise (SSN) environment. AT based on musical material has provided some evidence for an “auditory advantage” in understanding speech-in-noise (SIN), but with a long period training and complex procedure. Experimental research is essential to develop a simplified method named auditory target tracking training (ATT) which refined from musical material is necessary to determine the benefits of training. We developed two kinds of refined AT method: basic auditory target tracking (BAT) training and enhanced auditory target tracking (EAT) training to adult participants ([Formula: see text]) separately for 20 units, assessing performance to perceive speech in noise environment after training. The EAT group presented better speech perception performance than the other groups and no significant differences between BAT group and control group. The training effect of EAT is the most significant when uni-gender SSN and [Formula: see text] dB. Outcomes suggest that efficacy of trained EAT can improve speech perception performance and selective attention during SSN environment. These findings provide an important link between musical-based training and auditory selective attention in real-world, and extended to special vocational training.

Silencing cortical activity during sound-localization training impairs auditory perceptual learning

The brain has a remarkable capacity to adapt to changes in sensory inputs and to learn from experience. However, the neural circuits responsible for this flexible processing remain poorly understood. Using optogenetic silencing of ArchT-expressing neurons in adult ferrets, we show that within-trial activity in primary auditory cortex (A1) is required for training-dependent recovery in sound-localization accuracy following monaural deprivation. Because localization accuracy under normal-hearing conditions was unaffected, this highlights a specific role for cortical activity in learning. A1-dependent plasticity appears to leave a memory trace that can be retrieved, facilitating adaptation during a second period of monaural deprivation. However, in ferrets in which learning was initially disrupted by perturbing A1 activity, subsequent optogenetic suppression during training no longer affected localization accuracy when one ear was occluded. After the initial learning phase, the reweighting of spatial cues that primarily underpins this plasticity may therefore occur in A1 target neurons.

Increased sub-clinical levels of autistic traits are associated with reduced multisensory integration of audiovisual speech

Recent studies suggest that sub-clinical levels of autistic symptoms may be related to reduced processing of artificial audiovisual stimuli. It is unclear whether these findings extent to more natural stimuli such as audiovisual speech. The current study examined the relationship between autistic traits measured by the Autism spectrum Quotient and audiovisual speech processing in a large non-clinical population using a battery of experimental tasks assessing audiovisual perceptual binding, visual enhancement of speech embedded in noise and audiovisual temporal processing. Several associations were found between autistic traits and audiovisual speech processing. Increased autistic-like imagination was related to reduced perceptual binding measured by the McGurk illusion. Increased overall autistic symptomatology was associated with reduced visual enhancement of speech intelligibility in noise. Participants reporting increased levels of rigid and restricted behaviour were more likely to bind audiovisual speech stimuli over longer temporal intervals, while an increased tendency to focus on local aspects of sensory inputs was related to a more narrow temporal binding window. These findings demonstrate that increased levels of autistic traits may be related to alterations in audiovisual speech processing, and are consistent with the notion of a spectrum of autistic traits that extends to the general population.

The effectiveness of an auditory temporal training program in children who present voiceless/voiced-based orthographic errors

INTRODUCTION

Studies on children's written production of the Brazilian Portuguese have shown that one of the most frequent phonological-based orthographic errors is the one related to voiceless/voiced phonemes. Children who make this type of error may have auditory temporal processing disorders, which can harm the perception of phonemes with similar characteristics.

AIM

Verify the effectiveness of an auditory temporal training program based on activities adapted from the software Fast ForWord in the auditory temporal processing, i.e. the temporal ordering skill, and in reducing voiceless/voiced-based orthographic errors and the frequency of occurrence of these errors in the written production of the children.

METHOD

Twenty-five children participated on this study. They were divided in two groups: experimental group consisting of 16 participants, who engaged in the auditory temporal training activities; and a placebo group consisting of nine participants, who engaged in passive visual activities. The behavioral measures applied in the pre-training evaluation, post-training and placebo evaluations were: i) auditory skill of temporal ordering by the Pitch Pattern Sequence Test; and ii) analysis of the amount of voiceless/voiced-based orthographic errors and the frequency of occurrence of these errors by the use of dictation.

RESULTS

No statistically significant differences were found concerning the placebo group in the pre-training and post-training evaluations, in all evaluation measures. However, statistically significant differences were found in the pre-training and post-training evaluations for the pitch pattern sequence test concerning the experimental group. These differences were specifically related to a reduction of the errors regarding fricative graphemes, and the frequency of occurrence of plosive and fricative graphemes.

CONCLUSIONS

The auditory temporal training program was effective in improving the temporal ordering skill and reducing errors in the writing of children who made voiceless/voiced-based orthographic errors.

Age, Hearing, and the Perceptual Learning of Rapid Speech

The effects of aging and age-related hearing loss on the ability to learn degraded speech are not well understood. This study was designed to compare the perceptual learning of time-compressed speech and its generalization to natural-fast speech across young adults with normal hearing, older adults with normal hearing, and older adults with age-related hearing loss. Early learning (following brief exposure to time-compressed speech) and later learning (following further training) were compared across groups. Age and age-related hearing loss were both associated with declines in early learning. Although the two groups of older adults improved during the training session, when compared to untrained control groups (matched for age and hearing), learning was weaker in older than in young adults. Especially, the transfer of learning to untrained time-compressed sentences was reduced in both groups of older adults. Transfer of learning to natural-fast speech occurred regardless of age and hearing, but it was limited to sentences encountered during training. Findings are discussed within the framework of dynamic models of speech perception and learning. Based on this framework, we tentatively suggest that age-related declines in learning may stem from age differences in the use of high- and low-level speech cues. These age differences result in weaker early learning in older adults, which may further contribute to the difficulty to perceive speech in daily conversational settings in this population.

Effects of Manipulating the Amplitude of Consonant Noise Portion on Subcortical Representation of Voice Onset Time and Voicing Perception in Stop Consonants

Purpose The purpose of this study was to investigate whether speech perception would reflect small latency changes in subcortical speech representation. Method Twelve native Japanese listeners participated in the experiment. Those listeners participated in speech identification task and auditory brainstem response (ABR) measurement using /d/-/t/ continuum stimuli varying in voice onset time (VOT) with manipulation of the amplitude of initial noise (consonant) portion, the duration of which corresponded to VOT. Results Increasing the noise portion amplitude lengthened subcortical representation of VOT, which is the latency difference between ABRs synchronizing to the onsets of initial noise and following periodic (vowel) portions (VOT_ABR) and made listeners likely to perceive the stimuli with ambiguous VOT as a voiceless stop /t/. In addition, the amount of VOT_ABR lengthening was close to that of the VOT boundary shortening. Conclusion A few milliseconds of difference in subcortical speech representation are important for the perception of speech sounds with ambiguous acoustic cues. Supplemental Material https://doi.org/10.23641/asha.7728695.

Investigating peripheral sources of speech-in-noise variability in listeners with normal audiograms

A current initiative in auditory neuroscience research is to better understand why some listeners struggle to perceive speech-in-noise (SIN) despite having normal hearing sensitivity. Various hypotheses regarding the physiologic bases of this disorder have been proposed. Notably, recent work has suggested that the site of lesion underlying SIN deficits in normal hearing listeners may be either in "sub-clinical" outer hair cell damage or synaptopathic degeneration at the inner hair cell-auditory nerve fiber synapse. In this study, we present a retrospective investigation of these peripheral sources and their relationship with SIN performance variability in one of the largest datasets of young normal-hearing listeners presented to date. 194 participants completed detailed case history questionnaires assessing noise exposure, SIN complaints, tinnitus, and hyperacusis. Standard and extended high frequency audiograms, distortion product otoacoustic emissions, click-evoked auditory brainstem responses, and SIN performance measures were also collected. We found that: 1) the prevalence of SIN deficits in normal hearing listeners was 42% when based on subjective report and 8% when based on SIN performance, 2) hearing complaints and hyperacusis were more common in listeners with self-reported noise exposure histories than controls, 3) neither extended high frequency thresholds nor compound action potential amplitudes differed between noise-exposed and control groups, 4) extended high frequency hearing thresholds and compound action potential amplitudes were not predictive of SIN performance. These results suggest an association between noise exposure and hearing complaints in young, normal hearing listeners; however, SIN performance variability is not explained by peripheral auditory function to the extent that these measures capture subtle physiologic differences between participants.

Parameters for Applying the Brainstem Auditory Evoked Potential with Speech Stimulus: Systematic Review

Introduction  Studies using the Brainstem Auditory Evoked Potential with speech stimulus are increasing in Brazil, and there are divergences between the methodologies used for testing.

Objectives  To analyze the parameters used in the study of the Brainstem Auditory Evoked Potentials with speech stimulus.

Data Synthesis  The survey was performed using electronic databases. The search strategy was as follows: “Evoked potentials, auditory” OR “Brain stem” OR “Evoked potentials, auditory, brain stem” AND “Speech.” The survey was performed from June to July of 2016. The criteria used for including articles in this study were: being written in Portuguese, English or Spanish; presenting the description of the testing parameters and the description of the sample. In the databases selected, 2,384 articles were found, and 43 articles met all of the inclusion criteria. The predominance of the following parameters was observed to achieve the potential during study: stimulation with the syllable /da/; monaural presentation with greater use of the right ear; intensity of 80 dB SPL; vertical placement of electrodes; use of in-ear headphones; patient seated, distracted in awake state; alternating polarity; use of speech synthesizer software for the elaboration of stimuli; presentation rate of 10.9/s; and sampling rate of 20 kHz.

Conclusions  The theme addressed in this systematic review is relatively recent. However, the results are significant enough to encourage the use of the procedure in clinical practice and advise clinicians about the most used procedures in each parameter.