Normal-hearing Participants Research Articles

Reduced Channel Interaction Improves Timbre Recognition Under Vocoder Simulation of Cochlear Implant Processing.

This study aimed to investigate the influence of the number of channels and channel interaction on timbre perception in cochlear implant (CI) processing. By utilizing vocoder simulations of CI processing, the effects of different numbers of channels and channel interaction were examined to assess their impact on timbre perception, an essential aspect of music and auditory performance. Fourteen CI recipients, with at least 1 year of CI device use, and two groups (N = 16 and N = 19) of normal hearing (NH) participants completed a timbre recognition (TR) task. NH participants were divided into two groups, with each group being tested on different aspects of the study. The first group underwent testing with varying numbers of channels (8, 12, 16, and 20) to determine an ideal number that closely reflected the TR performance of CI recipients. Subsequently, the second group of NH participants participated in the assessment of channel interaction, utilizing the identified ideal number of 20 channels, with three conditions: low interaction (54 dB/octave), medium interaction (24 dB/octave), and high interaction (12 dB/octave). Statistical analyses, including repeated-measures analysis of variance and pairwise comparisons, were conducted to examine the effects. The number of channels did not demonstrate a statistically significant effect on TR in NH participants ( p > 0.05). However, it was observed that the condition with 20 channels closely resembled the TR performance of CI recipients. In contrast, channel interaction exhibited a significant effect ( p < 0.001) on TR. Both the low interaction (54 dB/octave) and high interaction (12 dB/octave) conditions differed significantly from the actual CI recipients' performance. Timbre perception, a complex ability reliant on highly detailed spectral resolution, was not significantly influenced by the number of channels. However, channel interaction emerged as a significant factor affecting timbre perception. The differences observed under different channel interaction conditions suggest potential mechanisms, including reduced spectro-temporal resolution and degraded spectral cues. These findings highlight the importance of considering channel interaction and optimizing CI processing strategies to enhance music perception and overall auditory performance for CI recipients.

Development of New Open-Set Speech Material for Use in Clinical Audiology with Speakers of British English.

The Chear open-set performance test (COPT), which uses a carrier phrase followed by a monosyllabic test word, is intended for clinical assessment of speech recognition, evaluation of hearing-device performance, and the fine-tuning of hearing devices for speakers of British English. This paper assesses practice effects, test-retest reliability, and the variability across lists of the COPT. In experiment 1, 16 normal-hearing participants were tested using an initial version of the COPT, at three speech-to-noise ratios (SNRs). Experiment 2 used revised COPT lists, with items swapped between lists to reduce differences in difficulty across lists. In experiment 3, test-retest repeatability was assessed for stimuli presented in quiet, using 15 participants with sensorineural hearing loss. After administration of a single practice list, no practice effects were evident. The critical difference between scores for two lists was about 2 words (out of 15) or 5 phonemes (out of 50). The mean estimated SNR required for 74% words correct was -0.56 dB, with a standard deviation across lists of 0.16 dB. For the participants with hearing loss tested in quiet, the critical difference between scores for two lists was about 3 words (out of 15) or 6 phonemes (out of 50).

Cochlear Implant Users Experience the Sound-To-Music Effect

ABSTRACT The speech-to-song illusion is a robust effect where repeated speech induces the perception of singing; this effect has been extended to repeated excerpts of environmental sounds (sound-to-music effect). Here, we asked whether repetition could elicit musical percepts in cochlear implant (CI) users, who experience challenges with perceiving music due to both physiological and device limitations. Thirty adult CI users and thirty age-matched controls with normal hearing (NH) completed two repetition experiments for speech and nonspeech sounds (water droplets). We hypothesized that CI users would experience the sound-to-music effect from temporal/rhythmic cues alone, but to a lesser magnitude compared to NH controls, given the limited access to spectral information CI users receive from their implants. We found that CI users did experience the sound-to-music effect but to a lesser degree compared to NH participants. Musicality ratings were not associated with musical training or frequency resolution, and among CI users, clinical variables like duration of hearing loss also did not influence ratings. Cochlear implants provide a strong clinical model for disentangling the effects of spectral and temporal information in an acoustic signal; our results suggest that temporal cues are sufficient to perceive the sound-to-music effect when spectral resolution is limited. Additionally, incorporating short repetitions into music specially designed for CI users may provide a promising way for them to experience music.

A Comparison of Montreal Cognitive Assessment Scores among Individuals with Normal Hearing and Cochlear Implants.

The Montreal Cognitive Assessment (MoCA) is a cognitive screening tool that has 4 of 10 test items heavily dependent on auditory input, potentially leaving hearing-impaired (HI) individuals at a disadvantage. Previous work found that HI individuals scored lower than normal-hearing (NH) individuals on the MoCA, potentially attributed to the degraded auditory signals negatively impacting the ability to commit auditory information to memory. However, there is no research comparing how cochlear implant (CI) recipients perform on the MoCA relative to NH and HI individuals. This study aimed to (1) examine the effect of implementing three different hearing-adjusted scoring methods for a group of age-matched CI recipients and NH individuals, (2) determine if there is a difference between the two groups in overall scores and hearing-adjusted scores, and (3) compare scores across our CI and NH data to the published HI data for all scoring methods. We hypothesized that (1) scores for CI recipients would improve with implementation of the hearing-adjusted scoring methods over the original method, (2) CI recipients would score lower than NH participants for both original and adjusted scoring methods, and (3) the difference in scores between NH and CI listeners for both adjusted and unadjusted scores would be greater than that reported in the literature between NH and HI individuals due to the greater severity of hearing loss and relatively poor spectral resolution of CIs. A total of 94 adults with CIs and 105 adults with NH were initially enrolled. After age-matching the two groups and excluding those who self-identified as NH but failed a hearing screening, a total of 75 CI participants (mean age 61.2 y) and 74 NH participants (mean age 58.8 y) were administered the MoCA. Scores were compared between the NH and CI groups, as well as to published HI data, using the original MoCA scoring method and three alternative scoring methods that excluded various auditory-dependent test items. MoCA scores improved for all groups when two of the three alternative scoring methods were used, with no significant interaction between scoring method and group. Scores for CI recipients were significantly poorer than those for age-matched NH participants for all scoring methods. CI recipients scored better than the published data for HI individuals; however, the HI group was not age matched to the CI and NH groups. MoCA scores are only partly affected by the potentially greater cognitive processing required to interpret degraded auditory signals. Even with the removal of the auditory-dependent items, CI recipients still did not perform as well as the age-matched NH group. Importantly, removing auditory-dependent items significantly and fundamentally alters the test, thereby reducing its sensitivity. This has important limitations for administration and interpretation of the MoCA for people with hearing loss.

Development of a Phrase-Based Speech-Recognition Test Using Synthetic Speech.

Speech-recognition tests are widely used in both clinical and research audiology. The purpose of this study was the development of a novel speech-recognition test that combines concepts of different speech-recognition tests to reduce training effects and allows for a large set of speech material. The new test consists of four different words per trial in a meaningful construct with a fixed structure, the so-called phrases. Various free databases were used to select the words and to determine their frequency. Highly frequent nouns were grouped into thematic categories and combined with related adjectives and infinitives. After discarding inappropriate and unnatural combinations, and eliminating duplications of (sub-)phrases, a total number of 772 phrases remained. Subsequently, the phrases were synthesized using a text-to-speech system. The synthesis significantly reduces the effort compared to recordings with a real speaker. After excluding outliers, measured speech-recognition scores for the phrases with 31 normal-hearing participants at fixed signal-to-noise ratios (SNR) revealed speech-recognition thresholds (SRT) for each phrase varying up to 4 dB. The median SRT was -9.1 dB SNR and thus comparable to existing sentence tests. The psychometric function's slope of 15 percentage points per dB is also comparable and enables efficient use in audiology. Summarizing, the principle of creating speech material in a modular system has many potential applications.

Development and validation of a French speech-in-noise self-test using synthetic voice in an adult population

BackgroundSpeech-in-noise (SIN) audiometry is a valuable part of audiological diagnostics and clinical measurements, providing information on an individual's ability to understand in noise. To date, such tests have been developed with natural voice presented monaurally or binaurally (via diotic and dichotic presentation). The time required to develop such tests is often long. The use of synthetic voice would simplify the test creation process and self-testing would improve accessibility.DesignMeasurements were performed using an Android tablet (Samsung Galaxy Tab A7) and calibrated Bluetooth headphones (Tilde Pro C, Orosound). Normative values were first defined using natural or synthetic voice on 69 normal-hearing participants. A total of 463 participants then undertook the SIN test comprising synthetic voice and dichotic antiphasic presentation. Of these, 399 also performed the SIN test with diotic presentation.ResultsNo significant differences in the speech reception threshold (SRT) were found between natural and synthetic voices for diotic presentations (p = 0.824, paired Student t-test) with normative values of −10.7 dB SNR (SD = 1.5 dB) and −10.4 dB SNR (SD = 1.4 dB), respectively. For the SoNoise test with synthetic voice and dichotic antiphasic presentation, the results showed a normative value of −17.5 dB SNR (SD = 1.5 dB), and a strong correlation (r = 0.797, p &amp;lt; 0.001) with the four-frequency pure-tone average (4f-PTA). Receiver operating curves (ROC) were then calculated: for a 4f-PTA of 20 dB hearing level (HL), the SRT was −14.5 dB SNR with a sensitivity of 84% and specificity of 89%. For a 4f-PTA of 30 dB HL, the SRT was −13.7 dB SNR with a sensitivity of 89% and specificity of 91%. For a 4f-PTA of 35 dB HL, the SRT was −13.0 dB SNR with a sensitivity of 88% and specificity of 93%. The normative binaural intelligibility level difference (BILD) value was 8.6 dB (SD = 2.0 dB) with normal-hearing participants. The learning effect due to the task and interface was 1.7 dB (1st to 7th test) and test duration was 3 min.ConclusionThe SoNoise test in its synthetic dichotic antiphasic presentation is a fast and reliable tool to diagnose hearing impairment at 20, 30, and 35 dB HL cut-offs.

Can listeners predict whether or not a stutter follows a stretch of fluent speech?

PurposeNeurophysiological studies report that people who stutter (PWS) exhibit enhanced motor preparation before they stutter. This motor preparation pattern raises the possibility of detecting upcoming stutter moments before they actually occur. This study examined whether these motor preparation differences are detectable by listeners in the corresponding acoustic signal, thereby allowing them to predict upcoming stuttering moments. If so, features in these acoustic patterns could potentially be employed by computational procedures to automate detection of upcoming stutters and to target auditory feedback alterations specifically on these locations. MethodsForty healthy normal-hearing participants (aged 18–30) listened to seemingly fluent speech extracts each of which was either followed by a fluent (control condition) or stuttered (experimental condition) moment after the fluent extract. Participants listened to each extract and rated the likelihood of the speaker stuttering on the next word on a scale of 1 (very unlikely) to 7 (very likely) as to whether they thought there was a subsequent stutter. Several measures were made on the speech extracts which were examined either as control requirements to ensure no differences between experimental and control material or as covariates to assess any effects they had on judgments between the two conditions. ResultsListeners gave significantly higher stutter-likelihood ratings for speech originally followed by a stuttered moment although effects were small. ConclusionsNaive listeners rated speech extracts that were subsequently followed by stuttered moments as more likely to be followed by a stutter than those that were followed by fluent words after the effects of significant covariates were excluded.

A standardised test to evaluate audio-visual speech intelligibility in French

ObjectiveLipreading, which plays a major role in the communication of the hearing impaired, lacked a French standardised tool. Our aim was to create and validate an audio-visual (AV) version of the French Matrix Sentence Test (FrMST). DesignVideo recordings were created by dubbing the existing audio files. SampleThirty-five young, normal-hearing participants were tested in auditory and visual modalities alone (Ao, Vo) and in AV conditions, in quiet, noise, and open and closed-set response formats. ResultsLipreading ability (Vo) ranged from 1 % to 77%-word comprehension. The absolute AV benefit was 9.25 dB SPL in quiet and 4.6 dB SNR in noise. The response format did not influence the results in the AV noise condition, except during the training phase. Lipreading ability and AV benefit were significantly correlated. ConclusionsThe French video material achieved similar AV benefits as those described in the literature for AV MST in other languages. For clinical purposes, we suggest targeting SRT80 to avoid ceiling effects, and performing two training lists in the AV condition in noise, followed by one AV list in noise, one Ao list in noise and one Vo list, in a randomised order, in open or close set-format.

Extending Subcortical EEG Responses to Continuous Speech to the Sound-Field.

The auditory brainstem response (ABR) is a valuable clinical tool for objective hearing assessment, which is conventionally detected by averaging neural responses to thousands of short stimuli. Progressing beyond these unnatural stimuli, brainstem responses to continuous speech presented via earphones have been recently detected using linear temporal response functions (TRFs). Here, we extend earlier studies by measuring subcortical responses to continuous speech presented in the sound-field, and assess the amount of data needed to estimate brainstem TRFs. Electroencephalography (EEG) was recorded from 24 normal hearing participants while they listened to clicks and stories presented via earphones and loudspeakers. Subcortical TRFs were computed after accounting for non-linear processing in the auditory periphery by either stimulus rectification or an auditory nerve model. Our results demonstrated that subcortical responses to continuous speech could be reliably measured in the sound-field. TRFs estimated using auditory nerve models outperformed simple rectification, and 16 minutes of data was sufficient for the TRFs of all participants to show clear wave V peaks for both earphones and sound-field stimuli. Subcortical TRFs to continuous speech were highly consistent in both earphone and sound-field conditions, and with click ABRs. However, sound-field TRFs required slightly more data (16 minutes) to achieve clear wave V peaks compared to earphone TRFs (12 minutes), possibly due to effects of room acoustics. By investigating subcortical responses to sound-field speech stimuli, this study lays the groundwork for bringing objective hearing assessment closer to real-life conditions, which may lead to improved hearing evaluations and smart hearing technologies.

Development of Singapore English speech audiometry test materials

Background Speech audiometry is utilised for diagnostic and rehabilitative purposes. Speech audiometry involves materials linguistic in nature. The ideal protocol is to have a tester who is a native or at least a fluent speaker of that language to conduct the test on a native listener. Except for a set of psychometrically equivalent word recordings that have yet to be validated, no other existing speech audiometry materials have been developed in Singapore English. Objective This study aims to develop and validate a local set of phonemically balanced English word lists for use on Singaporeans. Methods The first phase encompassed the development of spondaic and phonemically-balanced monosyllabic word lists for Speech Reception Threshold (SRT) and Word Recognition Score (WRS) testing. The second phase established perceptual equivalence across the monosyllabic word lists. The third phase encompassed the validation of these materials on 72 normal-hearing and hearing-impaired Singaporeans between 21 to 80 years old. Participants were tested with two spondaic and six monosyllabic word lists. Participants’ SRT and WRS values were analysed. Results The mean SRT and pure tone audiometry (PTA) average difference was 5.79 dB. All 43 normal-hearing participants achieved a maximum WRS of 100%, at an average presentation level of 28.1 dB above their PTA average. Test-retest analysis revealed clinically insignificant differences across all word lists. Conclusion The test materials are validated to be suitable for testing on Singaporean English speakers. Normative SRT and WRS data for Singaporeans have also been established.

HEARING LOSS AND FATIGUE IN MIDDLE-AGED AND OLDER ADULTS

Abstract Fatigue is associated with worse cognitive and physical functioning, psychosocial wellbeing, and quality of life. Hearing loss may be a risk factor for fatigue, perhaps through greater cognitive demand to compensate for degraded auditory signal. However, prior studies are predominantly in audiology clinical samples, which may be oversampled for individuals experiencing hearing-loss-related fatigue. We conducted a cross-sectional analysis including 3,031 participants from the National Health and Nutrition Examination Survey (NHANES) 2015-18. Fatigue was based on self-reported frequency of feeling tired or having little energy over the past 2 weeks. Hearing loss was defined as better-ear 4-frequency (0.5, 1, 2, 4 kilohertz) pure-tone average &amp;gt;25 decibels hearing level. Multivariable-adjusted multinomial logistic regression was used to model the relative risk ratios (RRR) of reporting a higher vs. reference frequency category of fatigue associated with hearing loss, adjusting for age, sex, race/ethnicity, education, smoking, drinking, occupational and off-work noise exposure, body mass index, comorbidities, and depressive symptoms. In this nationally representative sample of middle-aged and older adults (40-80 years, 48% male, 10% Black), 713 (24%) had hearing loss. When compared to normal-hearing participants, hearing-loss participants were more likely to report fatigue for more than half the days (RRR=2.16, 95% confidence interval [CI]: 1.24, 3.75) and nearly every day (RRR=2.09, 95% CI: 1.24, 3.52) relative to not feeling fatigue at all. Hearing loss is associated with fatigue at the population level. Public health efforts to manage hearing loss might improve fatigue and associated downstream health outcomes.

Effect of Cochlear Implantation on Social Life.

Explore the effects of hearing loss on social life and identify residual social life deficits that remain after cochlear implantation. Retrospective review of prospectively obtained data. Tertiary care adult neurotology center. Adults between the ages of 35 and 83 years were included with either normal hearing (NH) or a cochlear implant (CI). CI and non-CI-specific quality-of-life (QOL) surveys focused on social and overall QOL. (1) The difference in QOL survey responses between NH and CI participants. (2) The relationship between CI-specific global and social QOL responses and non-CI-specific social QOL responses in CI users. A total of 51 participants were included: 31 CI users and 20 NH participants. Of the social QOL questionnaires, CI users reported significantly poorer scores on Self-Efficacy in Social Interactions than NH peers ( p = 0.049). Both Self-Efficacy in Social Interactions scores and Social Isolation Questionnaire scores were significantly correlated with the CI-specific social domain of QOL ( r = 0.64 and -0.58, respectively). Only the Self-Efficacy in Social Interactions scores had a moderate association with global CI QOL ( r = 0.47). CI users self-report similar social life outcomes as their NH peers with the exception of poorer self-efficacy in social situations. Moreover, self-efficacy in social interactions and social isolation were associated with social QOL in CI users, and self-efficacy in social interactions was associated with broader CI-related QOL. Findings support the relevance of individuals' perception of social life to their overall QOL with a CI.

The effect of age on the hearing-related quality of life in normal-hearing adults

IntroductionRecently, a new holistic Patient Reported Outcome Measure (PROM) to assess hearing-related quality of life was developed, named the hearing-related quality of life questionnaire for Auditory-VIsual, COgnitive and Psychosocial functioning (hAVICOP). The purpose of the current study was to evaluate if the hAVICOP is sufficiently sensitive to detect an age effect in the hearing-related quality of life. MethodsOne-hundred thirteen normal-hearing participants (mean age: 42.13; range: 19 to 69 years) filled in the entire hAVICOP questionnaire online through the Research Electronic Data Capture surface. The hAVICOP consists of 27 statements, across three major subdomains (auditory-visual, cognitive, and psychosocial functioning), which have to be rated on a visual analogue scale ranging from 0 (rarely to never) to 100 (almost always). Mean scores were calculated for each subdomain separately as well as combined within a total score; the worse one's hearing-related quality of life, the lower the score. Linear regression models were run to predict the hAVICOP total as well as the three subdomain scores from age and sex. ResultsA significant main effect of age was observed for the total hAVICOP and all three subdomain scores, indicating a decrease in hearing-related quality of life with increasing age. For none of the analyses, a significant sex effect was found. ConclusionThe hAVICOP is sufficiently sensitive to detect an age effect in the hearing-related quality of life within a large group of normal-hearing adults, emphasizing its clinical utility. This age effect on the hearing-related quality of life might be related to the interplay of age-related changes in the bottom-up and top-down processes involved during speech processing.

Role of articulatory motor networks in perceptual categorization of speech signals: a 7T fMRI study.

Speech and language processing involve complex interactions between cortical areas necessary for articulatory movements and auditory perception and a range of areas through which these are connected and interact. Despite their fundamental importance, the precise mechanisms underlying these processes are not fully elucidated. We measured BOLD signals from normal hearing participants using high-field 7 Tesla fMRI with 1-mm isotropic voxel resolution. The subjects performed 2 speech perception tasks (discrimination and classification) and a speech production task during the scan. By employing univariate and multivariate pattern analyses, we identified the neural signatures associated with speech production and perception. The left precentral, premotor, and inferior frontal cortex regions showed significant activations that correlated with phoneme category variability during perceptual discrimination tasks. In addition, the perceived sound categories could be decoded from signals in a region of interest defined based on activation related to production task. The results support the hypothesis that articulatory motor networks in the left hemisphere, typically associated with speech production, may also play a critical role in the perceptual categorization of syllables. The study provides valuable insights into the intricate neural mechanisms that underlie speech processing.

Distinct roles of delta- and theta-band neural tracking for sharpening and predictive coding of multi-level speech features during spoken language processing.

The brain tracks and encodes multi-level speech features during spoken language processing. It is evident that this speech tracking is dominant at low frequencies (<8 Hz) including delta and theta bands. Recent research has demonstrated distinctions between delta- and theta-band tracking but has not elucidated how they differentially encode speech across linguistic levels. Here, we hypothesised that delta-band tracking encodes prediction errors (enhanced processing of unexpected features) while theta-band tracking encodes neural sharpening (enhanced processing of expected features) when people perceive speech with different linguistic contents. EEG responses were recorded when normal-hearing participants attended to continuous auditory stimuli that contained different phonological/morphological and semantic contents: (1) real-words, (2) pseudo-words and (3) time-reversed speech. We employed multivariate temporal response functions to measure EEG reconstruction accuracies in response to acoustic (spectrogram), phonetic and phonemic features with the partialling procedure that singles out unique contributions of individual features. We found higher delta-band accuracies for pseudo-words than real-words and time-reversed speech, especially during encoding of phonetic features. Notably, individual time-lag analyses showed that significantly higher accuracies for pseudo-words than real-words started at early processing stages for phonetic encoding (<100 ms post-feature) and later stages for acoustic and phonemic encoding (>200 and 400 ms post-feature, respectively). Theta-band accuracies, on the other hand, were higher when stimuli had richer linguistic content (real-words > pseudo-words > time-reversed speech). Such effects also started at early stages (<100 ms post-feature) during encoding of all individual features or when all features were combined. We argue these results indicate that delta-band tracking may play a role in predictive coding leading to greater tracking of pseudo-words due to the presence of unexpected/unpredicted semantic information, while theta-band tracking encodes sharpened signals caused by more expected phonological/morphological and semantic contents. Early presence of these effects reflects rapid computations of sharpening and prediction errors. Moreover, by measuring changes in EEG alpha power, we did not find evidence that the observed effects can be solitarily explained by attentional demands or listening efforts. Finally, we used directed information analyses to illustrate feedforward and feedback information transfers between prediction errors and sharpening across linguistic levels, showcasing how our results fit with the hierarchical Predictive Coding framework. Together, we suggest the distinct roles of delta and theta neural tracking for sharpening and predictive coding of multi-level speech features during spoken language processing.

Influence of cortical inhibition on auditory efferents in humans

Auditory activity in humans is influenced by feedback networks in the brain. The final leg of this pathway originates in the brainstem and plays an important role in protecting and aiding communication in competing noise. Previous studies have used auditory and/or visual attention tasks to manipulate cortical activity when exploring its influence on the periphery via the auditory efferent system. Using subjective attention does not control for variability across individuals in attentional state, alertness, and arousal. Hence, a consensus on the relationship between cortical activity and how it influences more caudal efferent reflexes is still needed. Here we describe the first assay to non-invasively influence the human auditory cortex activity using repetitive transcranial magnetic stimulation and measure its consequence on peripheral structures using otoacoustic emissions. We hypothesized that depressing brain activity temporarily affects auditory functioning. By instigating a virtual cortical lesion in normal hearing participants, we were able to characterize the influence that the auditory cortex has on the sensory cells in the cochlea, mediated via the medial olivocochlear reflex. Our results will open avenues for further research into new diagnostic and therapeutic approaches for hearing disorders.

Auditory reality and evaluation of hearing-aid function

Knowledge about people’s auditory reality (AR), i.e., the variety of listening demands and environments experienced in everyday life, is crucial when developing and evaluating hearing-aid function. We have previously investigated AR of older people with impaired hearing and generally seen an “easy” AR (many reports of passive listening and focused listening to TV, mainly in quiet). In the current study, we included participants with both normal and impaired hearing to investigate if participants with impaired hearing are avoiding difficult situations. The EMA study ran for a week with six daily prompts. In addition to the EMA survey items from our previous study, sound levels were recorded, and avoidance was investigated in an exit interview and by analyzing differences in AR between the groups. Preliminary analyses show that there were differences between the two groups in terms of where they were when they responded. The differences in listening task were small, but the participants with impaired hearing rated the reported situations to be more difficult than the normal-hearing participants. Our new results will be presented together with a discussion about the consequences of our auditory reality data on the way we evaluate hearing-aid function.

Dissociated neural tracking as an index of speech understanding in background noise

Human brain activity has been shown to track hierarchical linguistic units embedded in connected speech and these responses can be directly modulated by changes in speech intelligibility caused by spectral degradation or prior knowledge. In this study, we introduce a background noise and manipulate its level relative to the target speech to test the hypothesis that the tracking responses are modulated differently by the variations in Signal-to-Noise Ratio (SNR) and changes in speech intelligibility. Electroencephalography (EEG) responses to speech in quiet and in noise (multi-talker babble) at three different levels were measured from 19 normal hearing participants. Driven by the reduction in intelligibility, cortical coherence to “abstract” linguistic units with no accompanying acoustic cues was reduced relative to the “speech only” condition, and lateralized to single cerebral hemispheres. In contrast, brain responses coherent to words, aligned with acoustic onsets, were bilateral and reduced systematically as noise level increased. Strength of the tracking response correlated with subjective ratings from each participant on how much they can understand the speech sentences at all different linguistic levels. These results provide an objective and sensitive neural marker of speech intelligibility which can be further developed into clinical applications for objective assessment of speech-in-noise understanding.

Validation of a tablet-based application for hearing self-screening in an adult population

Objective This study evaluated the diagnostic performances of a tablet-based hearing screening test by assisted-test and self-test modes. Design/method Measurements were performed with the SoTone tests in normal hearing and hearing-impaired adult participants using an Android tablet and calibrated Bluetooth headphones. The duration of assisted- and self-test modes were compared. Receiver operating characteristic (ROC) curves were plotted after calculations of sensitivity and specificity at 20, 30, and 35 dB HL cut-off values. Study sample 217 participants performed the tests. The effect of test mode (assisted versus self) was compared in a sample of 103 participants. Results Self-test duration (89 s) was significantly longer than the assisted-test duration (75 s) (p = 0.003, Wilcoxon test). For the 20, 30, and 35 dB HL cut-off values, sensitivity was between 92% and 96%, and specificity was between 79 and 90%. Concordance of results between assisted-test and self-test modes was excellent (Cohen’s kappa = 0.81, p < 0.001). Conclusions The SoTone hearing screening test is accurate for identifying the presence of a suspected hearing loss at 20 dB HL or more in adults. It can be used either in assisted-test or self-test modes.

The Influence of Hearing Loss on the Pupil Response to Degraded Speech.

Current evidence regarding the influence of hearing loss on the pupil response elicited by speech perception is inconsistent. This might be partially due to confounding effects of age. This study aimed to compare pupil responses in age-matched groups of normal-hearing (NH) and hard of hearing (HH) listeners during listening to speech. We tested the baseline pupil size and mean and peak pupil dilation response of 17 NH participants (Mage = 46 years; age range: 20-62 years) and 17 HH participants (Mage = 45 years; age range: 20-63 years) who were pairwise matched on age and educational level. Participants performed three speech perception tasks at a 50% intelligibility level: noise-vocoded speech and speech masked with either stationary noise or interfering speech. They also listened to speech presented in quiet. Hearing loss was associated with poorer speech perception, except for noise-vocoded speech. In contrast to NH participants, performance of HH participants did not improve across trials for the interfering speech condition, and it decreased for speech in stationary noise. HH participants had a smaller mean pupil dilation in degraded speech conditions compared to NH participants, but not for speech in quiet. They also had a steeper decline in the baseline pupil size across trials. The baseline pupil size was smaller for noise-vocoded speech as compared to the other conditions. The normalized data showed an additional group effect on the baseline pupil response. Hearing loss is associated with a smaller pupil response and steeper decline in baseline pupil size during the perception of degraded speech. This suggests difficulties of the HH participants to sustain their effort investment and performance across the test session.