Hearing Listeners Research Articles

Evaluating the relationship between high-frequency hearing loss and front-back localization in the elderly

Sound localization is an essential ability for normal hearing listeners, aiding in the localization of objects and the detection of potential dangers, as well as enabling the extraction of target speech information in a noisy environment. However, high-frequency hearing loss, commonly observed in the elderly population, may lead to a decline in spatial localization ability. The present work evaluated the ability of horizontal localization of 60 elderly individuals in a psychoacoustic experiment and investigated the relationship between localization impairment and hearing loss in different frequency ranges. Results indicate that high-frequency hearing loss above 2 kHz has a minor impact on left-right localization, but significantly impairs front-back localization. The physical and psychoacoustic explanations are provided for the experimental observations.

Phoneme-related potentials recorded from normal hearing listeners and cochlear implant users in a selective attention paradigm to continuous speech

Cochlear implants can restore the ability to understand speech in patients with profound sensorineural hearing loss. At present, it is not fully understood how cochlear implant users perceive speech and how electric hearing provided by a cochlear implant differs from acoustic hearing. Phoneme-related potentials characterize neural responses to individual instances of phonemes extracted from continuous speech.This retrospective study investigated phoneme-related potentials in cochlear implant users in a selective attention paradigm. Responses were compared between normal hearing listeners and cochlear implant users, and between attended and unattended conditions. Differences between phoneme categories were compared and a classifier was trained to predict the phoneme category from the neural representation.The phoneme-related potentials of cochlear implant users showed similar responses to the ones obtained in normal hearing listeners for early responses (< 100 ms) but not for later responses (> 100 ms) where peaks were smaller or absent. Attention led to an enhancement of the response, whereas latency was mostly not affected by attention. The temporal morphology of the response was influenced by the phonetic features of the stimulus, allowing a classification of the phoneme category based on the phoneme-related potentials.There is a clinical need for methods that can rapidly and objectively assess the speech understanding performance of cochlear implant users. Phoneme-related potentials may provide such a link between the acoustic and the neural representations of phonemes. They may also reveal the challenges of individual subjects and thus provide indications for patient-specific auditory training, rehabilitation programs or the fitting of cochlear implant parameters.

Pupillometry reveals effects of pitch manipulation within and across words on listening effort and short-term memory.

For individuals with hearing loss, even successful speech communication comes at a cost. Cochlear implants transmit degraded information, specifically for voice pitch, which demands extra and sustained listening effort. The current study hypothesized that abnormal pitch patterns contribute to the additional listening effort, even in non-tonal language native speaking normally hearing listeners. We manipulated the fundamental frequency (F0)within and across words, while participants listen and repeat (simple intelligibility task), or listen, repeat, and later recall (concurrent encoding task) the words. In both experiments, the F0 manipulations resulted in small changes in intelligibility but no difference in free recall or subjective effort ratings. Pupillary metrics were yet sensitive to these manipulations: pupil dilations were larger when words were monotonized (flat contour) or inverted (the natural contour flipped upside-down), and larger when successive words were organized into a melodic pattern. The most likely interpretation is that the natural or expected F0 contour of a word contributes to its identity and facilitate its matching and retrieval from the phonological representation stored in long-term memory. Consequently, degrading words' F0 contour can result in extra listening effort. Our results call for solutions to improve pitch saliency and naturalness in future development of cochlear implants' signal processing strategies, even for non-tonal languages.

Increased listening effort and decreased speech discrimination at high presentation sound levels in acoustic hearing listeners and cochlear implant users.

The sounds we experience in our everyday communication can vary greatly in terms of level and background noise depending on the environment. Paradoxically, increasing the sound intensity may lead to worsened speech understanding, especially in noise. This is known as the "Rollover" phenomenon. There have been limited studies on rollover and how it is experienced differentially across aging groups, for those with and without hearing loss, as well as cochlear implant (CI) users. There is also mounting evidence that listening effort plays an important role in challenging listening conditions and can be directly quantified with objective measures such as pupil dilation. We found that listening effort was modulated by sound level and that rollover occurred primarily in the presence of background noise. The effect on listening effort was exacerbated by age and hearing loss in acoustic listeners, with greatest effect in older listeners with hearing loss, while there was no effect in CI users. The age- and hearing-dependent effects of rollover highlight the potential negative impact of amplification to high sound levels and therefore has implications for effective treatment of age-related hearing loss.

Effect of hearing aids on the externalization of everyday sounds.

This study examined the influence of stimulus properties on sound externalization when listening with hearing aids. Normally hearing listeners were presented with broadband "tokens" (environmental sounds and speech) from loudspeakers, and rated externalization using a continuous scale. In separate blocks, they listened unaided or while wearing behind-the-ear hearing aids with closed domes and low gain (linear or compressive). There was a significant influence of token on ratings, even for unaided listening, and the effect of hearing aids depended on token. An acoustic analysis indicated that hearing aids were more likely to disrupt externalization for peakier sounds with a low-frequency emphasis.

The temporal mismatch across listening sides affects cortical auditory evoked responses in normal hearing listeners and cochlear implant users with contralateral acoustic hearing

Combining a cochlear implant with contralateral acoustic hearing typically enhances speech understanding, although this improvement varies among CI users and can lead to an interference effect. This variability may be associated with the effectiveness of the integration between electric and acoustic stimulation, which might be affected by the temporal mismatch between the two listening sides. Finding methods to compensate for the temporal mismatch might contribute to the optimal adjustment of bimodal devices and to improve hearing in CI users with contralateral acoustic hearing.The current study investigates cortical auditory evoked potentials (CAEPs) in normal hearing listeners (NH) and CI users with contralateral acoustic hearing. In NH, the amplitude of the N1 peak and the maximum phase locking value (PLV) were analyzed under monaural, binaural, and binaural temporally mismatched conditions. In CI users, CAEPs were measured when listening with CI only (CIS_only), acoustically only (AS_only) and with both sides together (CIS+AS). When listening with CIS+AS, various interaural delays were introduced between the electric and acoustic stimuli.In NH listeners, interaural temporal mismatch resulted in decreased N1 amplitude and PLV. Moreover, PLV is suggested as a more sensitive measure to investigate the integration of information between the two listening sides.CI users showed varied N1 latencies between the AS_only and CIS_only listening conditions, with increased N1 amplitude when the temporal mismatch was compensated. A tendency towards increased PLV was also observed, however, to a lesser extent than in NH listeners, suggesting a limited integration between electric and acoustic stimulation.This work highlights the potential of CAEPs measurement to investigate cortical processing of the information between two listening sides in NH and bimodal CI users.

Listening Effort Measured With Pupillometry in Cochlear Implant Users Depends on Sound Level, But Not on the Signal to Noise Ratio When Using the Matrix Test.

We investigated whether listening effort is dependent on task difficulty for cochlear implant (CI) users when using the Matrix speech-in-noise test. To this end, we measured peak pupil dilation (PPD) at a wide range of signal to noise ratios (SNR) by systematically changing the noise level at a constant speech level, and vice versa. A group of mostly elderly CI users performed the Dutch/Flemish Matrix test in quiet and in multitalker babble at different SNRs. SNRs were set relative to the speech-recognition threshold (SRT), namely at SRT, and 5 and 10 dB above SRT (0 dB, +5 dB, and +10 dB re SRT). The latter 2 conditions were obtained by either varying speech level (at a fixed noise level of 60 dBA) or by varying noise level (with a fixed speech level). We compared these PPDs with those of a group of typical hearing (TH) listeners. In addition, listening effort was assessed with subjective ratings on a Likert scale. PPD for the CI group did not significantly depend on SNR, whereas SNR significantly affected PPDs for TH listeners. Subjective effort ratings depended significantly on SNR for both groups. For CI users, PPDs were significantly larger, and effort was rated higher when speech was varied, and noise was fixed for CI users. By contrast, for TH listeners effort ratings were significantly higher and performance scores lower when noise was varied, and speech was fixed. The lack of a significant effect of varying SNR on PPD suggests that the Matrix test may not be a feasible speech test for measuring listening effort with pupillometric measures for CI users. A rating test appeared more promising in this population, corroborating earlier reports that subjective measures may reflect different dimensions of listening effort than pupil dilation. Establishing the SNR by varying speech or noise level can have subtle, but significant effects on measures of listening effort, and these effects can differ between TH listeners and CI users.

The Effort of Repairing a Misperceived Word Can Impair Perception of Following Words, Especially for Listeners With Cochlear Implants.

In clinical and laboratory settings, speech recognition is typically assessed in a way that cannot distinguish accurate auditory perception from misperception that was mentally repaired or inferred from context. Previous work showed that the process of repairing misperceptions elicits greater listening effort, and that this elevated effort lingers well after the sentence is heard. That result suggests that cognitive repair strategies might appear successful when testing a single utterance but fail for everyday continuous conversational speech. The present study tested the hypothesis that the effort of repairing misperceptions has the consequence of carrying over to interfere with perception of later words after the sentence. Stimuli were open-set coherent sentences that were presented intact or with a word early in the sentence replaced with noise, forcing the listener to use later context to mentally repair the missing word. Sentences were immediately followed by digit triplets, which served to probe carryover effort from the sentence. Control conditions allowed for the comparison to intact sentences that did not demand mental repair, as well as to listening conditions that removed the need to attend to the post-sentence stimuli, or removed the post-sentence digits altogether. Intelligibility scores for the sentences and digits were accompanied by time-series measurements of pupil dilation to assess cognitive load during the task, as well as subjective rating of effort. Participants included adults with cochlear implants (CIs), as well as an age-matched group and a younger group of listeners with typical hearing for comparison. For the CI group, needing to repair a missing word during a sentence resulted in more errors on the digits after the sentence, especially when the repair process did not result in a coherent sensible perception. Sentences that needed repair also contained more errors on the words that were unmasked. All groups showed substantial increase of pupil dilation when sentences required repair, even when the repair was successful. Younger typical hearing listeners showed clear differences in moment-to-moment allocation of effort in the different conditions, while the other groups did not. For CI listeners, the effort of needing to repair misperceptions in a sentence can last long enough to interfere with words that follow the sentence. This pattern could pose a serious problem for regular communication but would go overlooked in typical testing with single utterances, where a listener has a chance to repair misperceptions before responding. Carryover effort was not predictable by basic intelligibility scores, but can be revealed in behavioral data when sentences are followed immediately by extra probe words such as digits.

Comparison of Psychometric Functions Measured Using Remote Testing and Laboratory Testing.

The use of remote testing to collect behavioral data has been on the rise, especially after the COVID-19 pandemic. Here we present psychometric functions for a commonly used speech corpus obtained in remote testing and laboratory testing conditions on young normal hearing listeners in the presence of different types of maskers. Headphone use for the remote testing group was checked by supplementing procedures from prior literature using a Huggins pitch task. Results revealed no significant differences in the measured thresholds using the remote testing and laboratory testing conditions for all the three masker types. Also, the thresholds measured obtained in these two conditions were strongly correlated for a different group of young normal hearing listeners. Based on the results, excellent outcomes on auditory threshold measurements where the stimuli are presented both at levels lower than and above an individual's speech-recognition threshold can be obtained by remotely testing the listeners.

Discrimination of rippled spectra with various ripple widths in listeners with normal and impaired hearing

In listeners aged 26 to 82 years with various degrees of hearing loss (from normal to moderate), the frequency resolving power (FRP) was assessed as the resolved ripple density resolution in rippled-spectrum signals at various ripple widths. In normal-hearing listeners, FRP increased with narrowing the ripple width. In impaired-hearing listeners, the effect of narrowing the ripple width was minor. The difference between the normal- and impaired-hearing listeners could not be explained by the excitation pattern model of the rippled spectrum resolution. The temporal analysis model did explain this difference on an assumption that in normal hearing listeners, enhancing the autocorrelation of the input signal resulted in prolongation of the delay at which the autocorrelation could be detected by the auditory system, whereas in impaired-hearing listeners this effect was reduced or absent.

Hebrew Digits in Noise (DIN) Test in Cochlear Implant Users and Normal Hearing Listeners.

This study aimed to compare the Hebrew version of the digits-in-noise (DIN) thresholds among cochlear implant (CI) users and their normal-hearing (NH) counterparts, explore the influence of age on these thresholds, examine the effects of early auditory exposure versus its absence on DIN threshold, and assess the correlation between DIN thresholds and other speech perception tests. A total of 13 children with CI (aged 5.5-11 years), 15 pre-lingual CI users (aged 14-30 years), and 15 post-lingual CI users (aged 22-77 years), and their age-matched NH controls (n = 45) participated in the study. Speech perception tasks, including the DIN test, one-syllable word test, and sentence identification tasks in various auditory conditions, served as the main outcome measures. The results indicated that CI users exhibited higher speech reception thresholds in noise across all age groups compared to NH peers, with no significant difference between pre-lingual and post-lingual CI users. Significant differences were also observed in monosyllabic word and sentence accuracy in both quiet and noise conditions between CI and NH groups. Furthermore, correlations were observed between the DIN and other speech perception tests. The study concludes that CI users require a notably higher signal-to-noise ratio to discern digits in noise, underscoring the DIN test's utility in assessing speech recognition capabilities in CI users while emphasizing the need for a comprehensive test battery to fully gauge their speech perception abilities.

Evaluating benefits of remote microphone technology for adults with hearing loss using behavioural and predictive metrics

Objective To investigate the benefit of remote-microphone (RM) systems for adults with sensory hearing loss. Design Speech recognition in quiet and in background noise was assessed. Participants with hearing loss underwent testing in two device conditions: hearing aids (HAs) alone and HAs with a RM. Normal hearing participants completed testing in the unaided condition. Predictive speech intelligibility modelling using the Hearing-Aid Speech Perception Index (HASPI) was also performed on recordings of HA processed test material. Study Sample Twenty adults with sensory hearing loss and 10 adults with normal hearing participated. Results Speech recognition for participants with hearing loss improved significantly when using the RM compared to HAs alone fit to Phonak’s proprietary prescription. Largest benefits were observed in the most challenging conditions. At the lowest signal-to-noise ratio, participants with hearing loss using a RM outperformed normal hearing listeners. Predicted intelligibility scores produced by HASPI were strongly correlated to behavioural results. Conclusions Adults using HAs who have significant difficulties understanding speech in noise will experience considerable benefits with the addition of a RM. Improvements in speech recognition were observed for all participants using RM systems, including those with relatively mild hearing loss. HASPI modelling reliably predicted the speech perception difficulties experienced.

A meta-analysis of expressive prosody in cochlear implant users

IntroductionProsody is used to express indexical (identifying the talker), linguistic (e.g., question intonation, lexical stress), pragmatic (e.g., contrastive stress, sarcasm), and emotional/affective functions. It is manifested through changes in fundamental frequency (f0), intensity, and duration. F0 and intensity are degraded when perceived through a cochlear implant (CI). The purpose of this meta-analysis is to compare expressive prosody in speech produced by CI users versus normal hearing peers. MethodsA systematic search of the literature found 25 articles that met all inclusion criteria. These articles were assessed for quality, and data pertaining to the expression of f0, intensity, and duration, as well as classification accuracy and appropriateness ratings from normal hearing listeners, were extracted and meta-analyzed using random effects models. ResultsThe articles included in the meta-analysis were generally of acceptable or high quality. Meta-analyses revealed significant differences between individuals with CIs vs. normal hearing on all measures except mean f0, mean intensity, and rhythm. Effect sizes were generally medium to large. There was significant heterogeneity across studies, but little evidence of publication bias. ConclusionsCI users speak with less variable f0, smaller f0 contours, more variable intensity, a slower speech rate, and reduced final lengthening at syntactic boundaries. These acoustic differences are reflected in significantly poorer ratings of speech produced by CI users compared to their normal hearing peers, as assessed by groups of normal hearing listeners. Because atypical expressive prosody is associated with negative outcomes, clinicians should consider targeting prosody when working with individuals who use CIs.

Can Inexperienced Listeners Hear Who Is Singing? The Role of Motivation in Singer Discrimination Across Pitch

Previous research has shown that in a task identifying singers across pitch, inexperienced listeners perform very poorly compared to their experienced counterparts. This poor performance may partially be due to lower motivation and reduced attention on the part of inexperienced listeners. The current experiment is designed to examine the role of motivation in difficult perceptual tasks through use of an established methodology that uses singing voice stimuli. This study used an ABX paradigm. Listeners heard two different singers, singing /ɑ/ at the same pitch and had to identify which of the two singers produced a third /ɑ/ at a different pitch. Pitches varied across 1.5 octaves. Inexperienced listeners were randomly assigned to 1 of 3 conditions: (1) no feedback, (2) percent correct feedback, and (3) percentile feedback. Prior to the experiment, listeners rated their motivation using the Situational Intrinsic Motivation Scale (SIMS). Data were collected from 99 inexperienced listeners. There were no significant differences between the three feedback conditions, No Feedback, Percent Correct, and Percentile, for any SIMS subscale. Likewise, there were no significant differences in musical experience between the three feedback conditions. A repeated measures ANOVA designed to test the effect of feedback group on mean percent correct responses revealed no significant main or interaction effects of feedback. However, amotivation was a significant predictor of mean percent correct scores. Motivation is a complex construct that, while not being a primary factor in the current audio-perceptual task, could still be an important confounding factor in perceptual research. In the case of the current study, the two feedback conditions utilized in this study, Percent Correct and Percentile, may not have provided sufficiently robust external motivation to elicit differences in performance. Perceptual and behavioral researchers should be vigilant. More research is necessary.

Rate dependent neural responses of interaural-time-difference cues in fine-structure and envelope.

Advancements in cochlear implants (CIs) have led to a significant increase in bilateral CI users, especially among children. Yet, most bilateral CI users do not fully achieve the intended binaural benefit due to potential limitations in signal processing and/or surgical implant positioning. One crucial auditory cue that normal hearing (NH) listeners can benefit from is the interaural time difference (ITD), i.e., the time difference between the arrival of a sound at two ears. The ITD sensitivity is thought to be heavily relying on the effective utilization of temporal fine structure (very rapid oscillations in sound). Unfortunately, most current CIs do not transmit such true fine structure. Nevertheless, bilateral CI users have demonstrated sensitivity to ITD cues delivered through envelope or interaural pulse time differences, i.e., the time gap between the pulses delivered to the two implants. However, their ITD sensitivity is significantly poorer compared to NH individuals, and it further degrades at higher CI stimulation rates, especially when the rate exceeds 300 pulse per second. The overall purpose of this research thread is to improve spatial hearing abilities in bilateral CI users. This study aims to develop electroencephalography (EEG) paradigms that can be used with clinical settings to assess and optimize the delivery of ITD cues, which are crucial for spatial hearing in everyday life. The research objective of this article was to determine the effect of CI stimulation pulse rate on the ITD sensitivity, and to characterize the rate-dependent degradation in ITD perception using EEG measures. To develop protocols for bilateral CI studies, EEG responses were obtained from NH listeners using sinusoidal-amplitude-modulated (SAM) tones and filtered clicks with changes in either fine structure ITD (ITDFS) or envelope ITD (ITDENV). Multiple EEG responses were analyzed, which included the subcortical auditory steady-state responses (ASSRs) and cortical auditory evoked potentials (CAEPs) elicited by stimuli onset, offset, and changes. Results indicated that acoustic change complex (ACC) responses elicited by ITDENV changes were significantly smaller or absent compared to those elicited by ITDFS changes. The ACC morphologies evoked by ITDFS changes were similar to onset and offset CAEPs, although the peak latencies were longest for ACC responses and shortest for offset CAEPs. The high-frequency stimuli clearly elicited subcortical ASSRs, but smaller than those evoked by lower carrier frequency SAM tones. The 40-Hz ASSRs decreased with increasing carrier frequencies. Filtered clicks elicited larger ASSRs compared to high-frequency SAM tones, with the order being 40 > 160 > 80> 320 Hz ASSR for both stimulus types. Wavelet analysis revealed a clear interaction between detectable transient CAEPs and 40-Hz ASSRs in the time-frequency domain for SAM tones with a low carrier frequency.

Sound-localization-related activation and functional connectivity of dorsal auditory pathway in relation to demographic, cognitive, and behavioral characteristics in age-related hearing loss.

Patients with age-related hearing loss (ARHL) often struggle with tracking and locating sound sources, but the neural signature associated with these impairments remains unclear. Using a passive listening task with stimuli from five different horizontal directions in functional magnetic resonance imaging, we defined functional regions of interest (ROIs) of the auditory "where" pathway based on the data of previous literatures and young normal hearing listeners (n = 20). Then, we investigated associations of the demographic, cognitive, and behavioral features of sound localization with task-based activation and connectivity of the ROIs in ARHL patients (n = 22). We found that the increased high-level region activation, such as the premotor cortex and inferior parietal lobule, was associated with increased localization accuracy and cognitive function. Moreover, increased connectivity between the left planum temporale and left superior frontal gyrus was associated with increased localization accuracy in ARHL. Increased connectivity between right primary auditory cortex and right middle temporal gyrus, right premotor cortex and left anterior cingulate cortex, and right planum temporale and left lingual gyrus in ARHL was associated with decreased localization accuracy. Among the ARHL patients, the task-dependent brain activation and connectivity of certain ROIs were associated with education, hearing loss duration, and cognitive function. Consistent with the sensory deprivation hypothesis, in ARHL, sound source identification, which requires advanced processing in the high-level cortex, is impaired, whereas the right-left discrimination, which relies on the primary sensory cortex, is compensated with a tendency to recruit more resources concerning cognition and attention to the auditory sensory cortex. Overall, this study expanded our understanding of the neural mechanisms contributing to sound localization deficits associated with ARHL and may serve as a potential imaging biomarker for investigating and predicting anomalous sound localization.

Estimating the high-frequency extent of binaural sensitivity to temporal fine structure across listeners

Füllgrabe et al. [2017, Int. J. Audiol. 56:926-35] developed a novel procedure to estimate the frequency dependence of listeners’ sensitivity to temporal fine structure in the form of interaural phase differences (IPD). Whereas traditional approaches fixed tone frequency and varied IPD, the new “TFS-AF” test fixed the IPD and varied frequencies adaptively so as to estimate the upper frequency limit (UFL) of IPD sensitivity, even in listeners who struggle with traditional tests. UFL estimates for young normal hearing listeners were consistently 1200–1400 Hz, with notable exceptions of lower UFL (e.g. 800–1000 Hz) in a small subset. The consistency of UFL and abrupt loss of IPD sensitivity above it remain among the most puzzling aspects of binaural hearing, unexplained by the (rather shallow) frequency dependence of audibility, neuronal phase locking, or internal noise in this region. Recently, our group adapted a version of the TFS-AF test to measure UFL as a function of sound level, comparing the resulting slope to predictions of candidate mechanisms. The limitation closely matches the upper edge of an auditory filter centered at ∼700 Hz, suggesting that IPD sensitivity is mediated exclusively by neurons tuned to that frequency or below. [Work supported by NIH R01DC014948, R01DC016643, and R01DC017924.]

Effects of training length on adaptation to noise-vocoded speech.

Listeners show rapid perceptual learning of acoustically degraded speech, though the amount of exposure required to maximize speech adaptation is unspecified. The current work used a single-session design to examine the length of auditory training on perceptual learning for normal hearing listeners exposed to eight-channel noise-vocoded speech. Participants completed short, medium, or long training using a two-alternative forced choice sentence identification task with feedback. To assess learning and generalization, a 40-trial pre-test and post-test transcription task was administered using trained and novel sentences. Training results showed all groups performed near ceiling with no reliable differences. For test data, we evaluated changes in transcription accuracy using separate linear mixed models for trained or novel sentences. In both models, we observed a significant improvement in transcription at post-test relative to pre-test. Critically, the three training groups did not differ in the magnitude of improvement following training. Subsequent Bayes factors analysis evaluating the test by group interaction provided strong evidence in support of the null hypothesis. For these stimuli and procedure, results suggest increased training does not necessarily maximize learning outcomes; both passive and trained experience likely supported adaptation. Findings may contribute to rehabilitation recommendations for listeners adapting to degraded speech signals.

Modified rhyme test performance and error patterns predict self-reported frequency of temporary threshold shifts for normal hearing listeners

After exposure to a loud sound, listeners may report that their hearing is dull or muffled. If hearing returns to pre-exposure levels, the change is considered a temporary threshold shift (TTS). TTSs are likely associated with damage to the auditory system. How frequently TTSs are experienced has been shown to be related to performance deficits on tasks like the modified rhyme test (MRT), even if audiometric thresholds are normal. The present study seeks to better understand the types of phonetic errors listeners with different frequencies of TTSs make on the MRT. Over 4000 US Service Members (SMs) completed the study. SMs were asked how frequently they experienced a TTS: “Never,” “Infrequent” ( &amp;lt; 1/year), or “Frequent” (≥1/ year). SMs completed 80 trials of a version of the MRT where SNR and target level were manipulated. Responses were analyzed using information theory and statistical modeling. Overall proportion correct, reaction time, and error rates associated with phonetic features were predictors of TTS frequency for normal hearing listeners. [The views expressed in this abstract are those of the authors and do not necessarily reflect the official policy of the Department of Defense or the U.S. Government.]

The contributions of acoustic and non-acoustic factors to spatial release from masking

The ability to identify speech at worse signal-to-noise ratios when the maskers are spatially separated compared to when they are colocated is called spatial release from masking (SRM) and is thought to be a combination of monaural and binaural advantages arising from spatially separating the target from the maskers. Also, a host of other cognitive skills including attention, working memory, and executive function that support listeners’ ability to segregate, track and attend to a “target” signal while tuning out other unwanted signals contributes to understanding speech better in complex environments. Previous research with young normal hearing listeners from our lab indicated that SRM was predicted by an individual’s ability to use binaural cues (ITD thresholds), switch attention between two streams of information (trail making test) and ability to suppress irrelevant information (flanker task). Here, we present data from older listeners with varying hearing abilities on acoustic (envITD sensitivity) and non-acoustic tasks measuring attention (auditory and visual single and dual task), processing (trail making task), executive control (flanker task) and speech in noise tests (spatial release from masking using coordinate Response Measure sentences). The relationship between these acoustic and non-acoustic factors to speech understanding in complex listening environments will be discussed.