Older Hearing-impaired Listeners Research Articles

The Cambridge aided loudness profile (CALP): item choices and data for unaided listening by young and older normal-hearing listeners and older hearing-impaired listeners

Objective To develop an improved version of the profile of aided loudness (PAL), intended for assessment of the appropriateness of the loudness of everyday sounds. Design Initially, 16 participants with a range of ages and degrees of hearing loss indicated whether they encountered each situation described in the PAL and how specific they considered the description to be. Based on the responses, most situations from the PAL were eliminated and new situations were introduced, giving the Cambridge Aided Loudness Profile (CALP). The CALP was administered to 80 young and 22 older participants with normal hearing, who rated the loudness of each situation and satisfaction with this loudness (as for the original PAL). Satisfaction was strongly negatively correlated with loudness, suggesting that satisfaction was largely based on loudness. The CALP was then administered to 32 new young normal-hearing participants and 49 older participants with hearing loss, most of whom used hearing aids, who rated loudness and the appropriateness of loudness. Results Some situations were rated as loud but appropriate in loudness, indicating that the CALP can distinguish these aspects. Conclusions The CALP questions were understood by all participants. The CALP may be useful for assessing the appropriateness of loudness.

Alpha-Band Dynamics of Hearing Aid Wearers Performing the Repeat-Recall Test (RRT).

This study measured electroencephalographic activity in the alpha band, often associated with task difficulty, to physiologically validate self-reported effort ratings from older hearing-impaired listeners performing the Repeat-Recall Test (RRT)-an integrative multipart assessment of speech-in-noise performance, context use, and auditory working memory. Following a single-blind within-subjects design, 16 older listeners (mean age = 71 years, SD = 13, 9 female) with a moderate-to-severe degree of bilateral sensorineural hearing loss performed the RRT while wearing hearing aids at four fixed signal-to-noise ratios (SNRs) of -5, 0, 5, and 10 dB. Performance and subjective ratings of listening effort were assessed for complementary versions of the RRT materials with high/low availability of semantic context. Listeners were also tested with a version of the RRT that omitted the memory (i.e., recall) component. As expected, results showed alpha power to decrease significantly with increasing SNR from 0 through 10 dB. When tested with high context sentences, alpha was significantly higher in conditions where listeners had to recall the sentence materials compared to conditions where the recall requirement was omitted. When tested with low context sentences, alpha power was relatively high irrespective of the memory component. Within-subjects, alpha power was related to listening effort ratings collected across the different RRT conditions. Overall, these results suggest that the multipart demands of the RRT modulate both neural and behavioral measures of listening effort in directions consistent with the expected/designed difficulty of the RRT conditions.

Relation between temporal fine structure processing and global processing speed

Strelcyk et al. (2019) recently found that interaural phase discrimination in older hearing-impaired listeners was correlated with both visuospatial processing speed and interaural level discrimination. This suggests that temporal fine structure (TFS) processing relies on global processing speed and/or spatial cognition, though it is possible that, generally, complex auditory discrimination engages multiple cognitive domains. Here, 50 Veterans (mean age = 48.1, range = 30–60) with normal or near-normal hearing completed batteries of temporal processing and cognitive tests. Composite cognitive test scores reflecting processing speed/executive function (PS-EX) and working memory (WM) were obtained. Temporal processing tasks included measures of envelope (ENV; gap duration discrimination, forward masking) and TFS (frequency modulation detection, interaural phase modulation detection) processing. Bayesian hierarchical regression was used to fit psychometric functions simultaneously to all ENV and TFS tasks in all subjects. Fixed effects of PS-EX and WM on thresholds and slopes were estimated for the psychometric functions in each temporal task. In general, (i) PS-EX and WM influenced both TFS and ENV thresholds, but not slopes; and (ii) TFS thresholds were best explained by PS-EX scores while ENV thresholds were best explained by WM scores. These findings suggest a specific relation between global processing speed and TFS.

Rate Discrimination Training May Partially Restore Temporal Processing Abilities from Age-Related Deficits.

The ability to understand speech in complex environments depends on the brain’s ability to preserve the precise timing characteristics of the speech signal. Age-related declines in temporal processing may contribute to the older adult’s experience of communication difficulty in challenging listening conditions. This study’s purpose was to evaluate the effects of rate discrimination training on auditory temporal processing. A double-blind, randomized control design assigned 77 young normal-hearing, older normal-hearing, and older hearing-impaired listeners to one of two treatment groups: experimental (rate discrimination for 100- and 300-Hz pulse trains) and active control (tone detection in noise). All listeners were evaluated during pre- and post-training sessions using perceptual rate discrimination of 100-, 200-, 300-, and 400-Hz band-limited pulse trains and auditory steady-state responses (ASSRs) to the same stimuli. Training generalization was evaluated using several temporal processing measures and sentence recognition tests that included time-compressed and reverberant speech stimuli. Results demonstrated a session × training group interaction for perceptual and ASSR testing to the trained frequencies (100 and 300 Hz), driven by greater improvements in the training group than in the active control group. Further, post-test rate discrimination of the older listeners reached levels that were equivalent to those of the younger listeners at pre-test. Generalization was observed in significant improvement in rate discrimination of untrained frequencies (200 and 400 Hz) and in correlations between performance changes in rate discrimination and sentence recognition of reverberant speech. Further, non-auditory inhibition/attention performance predicted training-related improvement in rate discrimination. Overall, the results demonstrate the potential for auditory training to partially restore temporal processing in older listeners and highlight the role of cognitive function in these gains.

The effects of aging and hearing loss on the across-frequency processing of interaural time differences

Aging and hearing loss cause speech understanding deficits, particularly in the presence of competing sounds, as well as temporal processing deficits, including binaural encoding of interaural time differences (ITDs). However, there is little understanding of the independent effects of aging and hearing loss on across-frequency ITD processing, which demonstrates a clear dependence on frequency weighting or “dominant” region around 600–700Hz. We hypothesize that aging and hearing loss will reduce extent of laterality of ITDs and will shift the frequency weighting lower. Young normal-hearing, older normal-hearing, and older hearing-impaired listeners will be tested on an intracranial lateralization task. The stimuli will consist of narrowband noises. They will have upper frequency boundaries = 500, 600, 700, or 800 Hz, bandwidths = 50, 100, 200, or 400 Hz, and ITDs = 0, ±0.5, ±1, ±1.5, and ±2 ms. These findings will help us better understand the role of the dominant region in across-frequency ITD processing, and how age- and hearing-loss-related changes in ITD processing may contribute to spatial-hearing deficits.

Effects of aging and hearing loss on perceptual and electrophysiological measures of pulse-rate discrimination.

Auditory temporal processing declines with age, leading to potential deleterious effects on communication. In young normal-hearing listeners, perceptual rate discrimination is rate limited around 300 Hz. It is not known whether this rate limitation is similar in older listeners with hearing loss. The purpose of this study was to investigate age- and hearing-loss-related rate limitations on perceptual rate discrimination, and age- and hearing-loss-related effects on neural representation of these stimuli. Younger normal-hearing, older normal-hearing, and older hearing-impaired listeners performed a pulse-rate discrimination task at rates of 100, 200, 300, and 400 Hz. Neural phase locking was assessed using the auditory steady-state response. Finally, a battery of non-auditory cognitive tests was administered. Younger listeners had better rate discrimination, higher phase locking, and higher cognitive scores compared to both groups of older listeners. Aging, but not hearing loss, diminished neural-rate encoding and perceptual performance; however, there was no relationship between the perceptual and neural measures. Higher cognitive scores were correlated with improved perceptual performance, but not with neural phase locking. This study shows that aging, rather than hearing loss, may be a stronger contributor to poorer temporal processing, and cognitive factors such as processing speed and inhibitory control may be related to these declines.

Revealing Perceptional and Cognitive Mechanisms in Static and Dynamic Cocktail Party Listening by Means of Error Analyses.

In cocktail party situations multiple talkers speak simultaneously, which causes listening to be perceptually and cognitively challenging. Such situations can either be static (fixed target talker) or dynamic, meaning the target talker switches occasionally and in a potentially unpredictable way. To shed light on the perceptional and cognitive mechanisms in static and dynamic cocktail party situations, we conducted an analysis of error types that occur during a multi-talker speech recognition test. The error analysis distinguished between misunderstood or omitted words (random errors) and target-masker confusions. To investigate the effects of aging and hearing impairment, we compared data from three listener groups, comprised of young as well as older adults with and without hearing loss. In the static condition, error rates were generally very low, except for the older hearing-impaired listeners. Consistent with the assumption of decreased audibility, they showed a notable amount of random errors. In the dynamic condition, errors increased compared to the static condition, especially immediately following a target talker switch. Those increases were similar for random and confusion errors. The older hearing-impaired listeners showed greater difficulties than the younger adults in trials not preceded by a switch. These results suggest that the load associated with dynamic cocktail party listening affects the ability to focus attention on the talker of interest and the retrieval of words from short-term memory, as indicated by the increased amount of confusion and random errors. This was most pronounced in the older hearing-impaired listeners proposing an interplay of perceptual and cognitive mechanisms.

Hearing-Aid Directionality Improves Neural Speech Tracking in Older Hearing-Impaired Listeners.

In recent years, a growing body of literature has explored the effect of hearing impairment on the neural processing of speech, particularly related to the neural tracking of speech envelopes. However, only limited work has focused on the potential usage of the method for evaluating the effect of hearing aids designed to amplify and process the auditory input provided to hearing-impaired listeners. The current study investigates how directional sound processing in hearing-aids, denoted directionality, affects the neural tracking and encoding of speech in EEG recorded from 11 older hearing-impaired listeners. Behaviorally, the task performance improved when directionality was applied, while subjective ratings of listening effort were not affected. The reconstruction of the to-be-attended speech envelopes improved significantly when applying directionality, as well as when removing the background noise altogether. When inspecting the modelled response of the neural encoding of speech, a faster transition was observed between the early bottom-up response and the later top-down attentional-driven responses when directionality was applied. In summary, hearing-aid directionality affects both the neural speech tracking and neural encoding of to-be-attended speech. This result shows that hearing-aid signal processing impacts the neural processing of sounds and that neural speech tracking is indicative of the benefits associated with applying hearing-aid processing algorithms.

Tracking Musical Voices in Bach's The Art of the Fugue: Timbral Heterogeneity Differentially Affects Younger Normal-Hearing Listeners and Older Hearing-Aid Users

Auditory scene analysis is an elementary aspect of music perception, yet only little research has scrutinized auditory scene analysis under realistic musical conditions with diverse samples of listeners. This study probed the ability of younger normal-hearing listeners and older hearing-aid users in tracking individual musical voices or lines in JS Bach's The Art of the Fugue. Five-second excerpts with homogeneous or heterogenous instrumentation of 2–4 musical voices were presented from spatially separated loudspeakers and preceded by a short cue for signaling the target voice. Listeners tracked the cued voice and detected whether an amplitude modulation was imposed on the cued voice or a distractor voice. Results indicated superior performance of young normal-hearing listeners compared to older hearing-aid users. Performance was generally better in conditions with fewer voices. For young normal-hearing listeners, there was interaction between the number of voices and the instrumentation: performance degraded less drastically with an increase in the number of voices for timbrally heterogeneous mixtures compared to homogeneous mixtures. Older hearing-aid users generally showed smaller effects of the number of voices and instrumentation, but no interaction between the two factors. Moreover, tracking performance of older hearing aid users did not differ when these participants did or did not wear hearing aids. These results shed light on the role of timbral differentiation in musical scene analysis and suggest reduced musical scene analysis abilities of older hearing-impaired listeners in a realistic musical scenario.

Identification and Discrimination of Sound Textures in Hearing-Impaired and Older Listeners.

Sound textures are a broad class of sounds defined by their homogeneous temporal structure. It has been suggested that sound texture perception is mediated by time-averaged summary statistics measured from early stages of the auditory system. The ability of young normal-hearing (NH) listeners to identify synthetic sound textures increases as the statistics of the synthetic texture approach those of its real-world counterpart. In sound texture discrimination, young NH listeners utilize the fine temporal stimulus information for short-duration stimuli, whereas they switch to a time-averaged statistical representation as the stimulus’ duration increases. The present study investigated how younger and older listeners with a sensorineural hearing impairment perform in the corresponding texture identification and discrimination tasks in which the stimuli were amplified to compensate for the individual listeners’ loss of audibility. In both hearing impaired (HI) listeners and NH controls, sound texture identification performance increased as the number of statistics imposed during the synthesis stage increased, but hearing impairment was accompanied by a significant reduction in overall identification accuracy. Sound texture discrimination performance was measured across listener groups categorized by age and hearing loss. Sound texture discrimination performance was unaffected by hearing loss at all excerpt durations. The older listeners’ sound texture and exemplar discrimination performance decreased for signals of short excerpt duration, with older HI listeners performing better than older NH listeners. The results suggest that the time-averaged statistic representations of sound textures provide listeners with cues which are robust to the effects of age and sensorineural hearing loss.

Senescent Decline in Verbal-Emotion Identification by Older Hearing-Impaired Listeners - Do Hearing Aids Help?

PurposeTo assess the ability of older-adult hearing-impaired (OHI) listeners to identify verbal expressions of emotions, and to evaluate whether hearing-aid (HA) use improves identification performance in those listeners.MethodsTwenty-nine OHI listeners, who were experienced bilateral-HA users, participated in the study. They listened to a 20-sentence-long speech passage rendered with six different emotional expressions (“happiness”, “pleasant surprise”, “sadness”, “anger”, “fear”, and “neutral”). The task was to identify the emotion portrayed in each version of the passage. Listeners completed the task twice in random order, once unaided, and once wearing their own bilateral HAs. Seventeen young-adult normal-hearing (YNH) listeners were also tested unaided as controls.ResultsMost YNH listeners (89.2%) correctly identified emotions compared to just over half of the OHI listeners (58.7%). Within the OHI group, verbal emotion identification was significantly correlated with age, but not with audibility-related factors. The number of OHI listeners who were able to correctly identify the different emotions did not significantly change when HAs were worn (54.8%).ConclusionIn line with previous investigations using shorter speech stimuli, there were clear age differences in the recognition of verbal emotions, with OHI listeners showing a significant reduction in unaided verbal-emotion identification performance that progressively declined with age across older adulthood. Rehabilitation through HAs did not provide compensation for the impaired ability to perceive emotions carried by speech sounds.

Clinical validation of the Russian Matrix test – effect of hearing loss, age, and noise level

Objective To validate the Russian matrix sentence test (RUMatrix) for the assessment of speech recognition in quiet and in noise in clinical praxis. The effect of hearing impairment, age, and masking-noise level on speech recognition was examined. Design All participants underwent pure tone audiometry, a monosyllabic speech test in quiet, and speech recognition measurements with RUMatrix in quiet (SRTQ) and in noise (SRTN). Study sample One hundred and forty-two listeners divided into four groups: 1. Young normal-hearing listeners, 2. Older normal-hearing listeners, 3. Young hearing-impaired listeners, and 4. Older hearing-impaired listeners. Results Significant differences between groups of listeners were found in the SRTQ and SRTN. A strong correlation between hearing threshold and SRTQ (R2=0.88, p < 0.001) indicates a strong link between speech recognition in quiet and audibility. The pure-tone average explained less variance in SRTN (R2=0.67, p < 0.001), pointing out an additional influence of suprathreshold distortion. A high test sensitivity of 0.99 was found for SRTN and SRTQ. The monosyllabic test had a low sensitivity (0.21), indicating that the test is not suitable for separating normal-hearing and hearing-impaired listeners. Conclusions RuMatrix is a reliable speech recognition assessment tool with a high sensitivity and validity for the main aspects of hearing impairment.

Suprathreshold Differences in Competing Speech Perception in Older Listeners With Normal and Impaired Hearing.

Purpose Age-related declines in auditory temporal processing and cognition make older listeners vulnerable to interference from competing speech. This vulnerability may be increased in older listeners with sensorineural hearing loss due to additional effects of spectral distortion and accelerated cognitive decline. The goal of this study was to uncover differences between older hearing-impaired (OHI) listeners and older normal-hearing (ONH) listeners in the perceptual encoding of competing speech signals. Method Age-matched groups of 10 OHI and 10 ONH listeners performed the coordinate response measure task with a synthetic female target talker and a male competing talker at a target-to-masker ratio of +3 dB. Individualized gain was provided to OHI listeners. Each listener completed 50 baseline and 800 "bubbles" trials in which randomly selected segments of the speech modulation power spectrum (MPS) were retained on each trial while the remainder was filtered out. Average performance was fixed at 50% correct by adapting the number of segments retained. Multinomial regression was used to estimate weights showing the regions of the MPS associated with performance (a "classification image" or CImg). Results The CImg weights were significantly different between the groups in two MPS regions: a region encoding the shared phonetic content of the two talkers and a region encoding the competing (male) talker's voice. The OHI listeners demonstrated poorer encoding of the phonetic content and increased vulnerability to interference from the competing talker. Individual differences in CImg weights explained over 75% of the variance in baseline performance in the OHI listeners, whereas differences in high-frequency pure-tone thresholds explained only 10%. Conclusion Suprathreshold deficits in the encoding of low- to mid-frequency (~5-10 Hz) temporal modulations-which may reflect poorer "dip listening"-and auditory grouping at a perceptual and/or cognitive level are responsible for the relatively poor performance of OHI versus ONH listeners on a different-gender competing speech task. Supplemental Material https://doi.org/10.23641/asha.12568472.

The Adaptation to Mandarin-Accented English by Older, Hearing-Impaired Listeners Following Brief Exposure to the Accent.

Purpose The language processing of Mandarin-accented English (MAE) by older hearing-impaired (OHI), older normally hearing (NH), and younger NH listeners was explored. We examined whether OHI adults have more difficulty than NH listeners in recognizing and adapting to MAE speech productions after receiving brief training with the accent. Method Talker-independent adaptation was evaluated in an exposure training study design. Listeners were trained either by four MAE talkers or four Australian English talkers (control group) before listening to sentences presented by a novel MAE talker. Speech recognition for both the training sentences and the experimental sentences were compared between listener groups and between the training accents. Results Listeners in all three groups (OHI, older NH, younger NH) who had been trained by the MAE talkers showed higher odds of speech recognition than listeners trained by the Australian English talkers. The OHI listeners adapted to MAE to the same degree as the NH groups despite returning lower overall odds of recognizing MAE speech. Conclusions Older listeners with mild-to-moderate hearing loss were able to benefit as much from brief exposure to MAE as did the NH groups. This encouraging result suggests that OHI listeners have access to and can exploit the information present in a relatively brief sample of accented speech and generalize their learning to a novel MAE talker.

Effects of Sensorineural Hearing Loss on Cortical Synchronization to Competing Speech during Selective Attention.

When selectively attending to a speech stream in multi-talker scenarios, low-frequency cortical activity is known to synchronize selectively to fluctuations in the attended speech signal. Older listeners with age-related sensorineural hearing loss (presbycusis) often struggle to understand speech in such situations, even when wearing a hearing aid. Yet, it is unclear whether a peripheral hearing loss degrades the attentional modulation of cortical speech tracking. Here, we used psychoacoustics and electroencephalography (EEG) in male and female human listeners to examine potential effects of hearing loss on EEG correlates of speech envelope synchronization in cortex. Behaviorally, older hearing-impaired (HI) listeners showed degraded speech-in-noise recognition and reduced temporal acuity compared with age-matched normal-hearing (NH) controls. During EEG recordings, we used a selective attention task with two spatially separated simultaneous speech streams where NH and HI listeners both showed high speech recognition performance. Low-frequency (<10 Hz) envelope-entrained EEG responses were enhanced in the HI listeners, both for the attended speech, but also for tone sequences modulated at slow rates (4 Hz) during passive listening. Compared with the attended speech, responses to the ignored stream were found to be reduced in both HI and NH listeners, allowing for the attended target to be classified from single-trial EEG data with similar high accuracy in the two groups. However, despite robust attention-modulated speech entrainment, the HI listeners rated the competing speech task to be more difficult. These results suggest that speech-in-noise problems experienced by older HI listeners are not necessarily associated with degraded attentional selection.SIGNIFICANCE STATEMENT People with age-related sensorineural hearing loss often struggle to follow speech in the presence of competing talkers. It is currently unclear whether hearing impairment may impair the ability to use selective attention to suppress distracting speech in situations when the distractor is well segregated from the target. Here, we report amplified envelope-entrained cortical EEG responses to attended speech and to simple tones modulated at speech rates (4 Hz) in listeners with age-related hearing loss. Critically, despite increased self-reported listening difficulties, cortical synchronization to speech mixtures was robustly modulated by selective attention in listeners with hearing loss. This allowed the attended talker to be classified from single-trial EEG responses with high accuracy in both older hearing-impaired listeners and age-matched normal-hearing controls.

Can You Hear Out the Melody? Testing Musical Scene Perception in Young Normal-Hearing and Older Hearing-Impaired Listeners.

It is well known that hearing loss compromises auditory scene analysis abilities, as is usually manifested in difficulties of understanding speech in noise. Remarkably little is known about auditory scene analysis of hearing-impaired (HI) listeners when it comes to musical sounds. Specifically, it is unclear to which extent HI listeners are able to hear out a melody or an instrument from a musical mixture. Here, we tested a group of younger normal-hearing (yNH) and older HI (oHI) listeners with moderate hearing loss in their ability to match short melodies and instruments presented as part of mixtures. Four-tone sequences were used in conjunction with a simple musical accompaniment that acted as a masker (cello/piano dyads or spectrally matched noise). In each trial, a signal-masker mixture was presented, followed by two different versions of the signal alone. Listeners indicated which signal version was part of the mixture. Signal versions differed either in terms of the sequential order of the pitch sequence or in terms of timbre (flute vs. trumpet). Signal-to-masker thresholds were measured by varying the signal presentation level in an adaptive two-down/one-up procedure. We observed that thresholds of oHI listeners were elevated by on average 10 dB compared with that of yNH listeners. In contrast to yNH listeners, oHI listeners did not show evidence of listening in dips of the masker. Musical training of participants was associated with a lowering of thresholds. These results may indicate detrimental effects of hearing loss on central aspects of musical scene perception.

Exploring Differences in Speech Processing Among Older Hearing-Impaired Listeners With or Without Hearing Aid Experience: Eye-Tracking and fMRI Measurements.

Recently, evidence has been accumulating that untreated hearing loss can lead to neurophysiological changes that affect speech processing abilities in noise. To shed more light on how aiding may impact these effects, this study explored the influence of hearing aid (HA) experience on the cognitive processes underlying speech comprehension. Eye-tracking and functional magnetic resonance imaging (fMRI) measurements were carried out with acoustic sentence-in-noise (SiN) stimuli complemented by pairs of pictures that either correctly (target picture) or incorrectly (competitor picture) depicted the sentence meanings. For the eye-tracking measurements, the time taken by the participants to start fixating the target picture (the ‘processing time’) was measured. For the fMRI measurements, brain activation inferred from blood-oxygen-level dependent responses following sentence comprehension was measured. A noise-only condition was also included. Groups of older hearing-impaired individuals matched in terms of age, hearing loss, and working memory capacity with (eHA; N = 13) or without (iHA; N = 14) HA experience participated. All acoustic stimuli were presented via earphones with individual linear amplification to ensure audibility. Consistent with previous findings, the iHA group had significantly longer (poorer) processing times than the eHA group, despite no differences in speech recognition performance. Concerning the fMRI measurements, there were indications of less brain activation in some right frontal areas for SiN relative to noise-only stimuli in the eHA group compared to the iHA group. Together, these results suggest that HA experience leads to faster speech-in-noise processing, possibly related to less recruitment of brain regions outside the core sentence-comprehension network. Follow-up research is needed to substantiate the findings related to changes in cortical speech processing with HA use.

Identification of the Spectrotemporal Modulations That Support Speech Intelligibility in Hearing-Impaired and Normal-Hearing Listeners.

Purpose Age-related sensorineural hearing loss can dramatically affect speech recognition performance due to reduced audibility and suprathreshold distortion of spectrotemporal information. Normal aging produces changes within the central auditory system that impose further distortions. The goal of this study was to characterize the effects of aging and hearing loss on perceptual representations of speech. Method We asked whether speech intelligibility is supported by different patterns of spectrotemporal modulations (STMs) in older listeners compared to young normal-hearing listeners. We recruited 3 groups of participants: 20 older hearing-impaired (OHI) listeners, 19 age-matched normal-hearing listeners, and 10 young normal-hearing (YNH) listeners. Listeners performed a speech recognition task in which randomly selected regions of the speech STM spectrum were revealed from trial to trial. The overall amount of STM information was varied using an up-down staircase to hold performance at 50% correct. Ordinal regression was used to estimate weights showing which regions of the STM spectrum were associated with good performance (a "classification image" or CImg). Results The results indicated that (a) large-scale CImg patterns did not differ between the 3 groups; (b) weights in a small region of the CImg decreased systematically as hearing loss increased; (c) CImgs were also nonsystematically distorted in OHI listeners, and the magnitude of this distortion predicted speech recognition performance even after accounting for audibility; and (d) YNH listeners performed better overall than the older groups. Conclusion We conclude that OHI/older normal-hearing listeners rely on the same speech STMs as YNH listeners but encode this information less efficiently. Supplemental Material https://doi.org/10.23641/asha.7859981.

Effects of age, modulation rate, and modulation depth on sentence recognition in speech-modulated noise

Speech is often heard in amplitude modulated backgrounds when speech is glimpsed during momentary masker dips. Increased masker modulation depth provides more improvement in the signal-to-noise ratio of glimpsed speech, but also improves noise modulation detection for potentially greater modulation masking. Mechanisms of modulation masking and glimpsing may also depend on the overlap of the modulation spectra of the speech and noise. This study employed modulation filtering and noise amplitude compression to investigate the combined effects of noise modulation depth and modulation rate on speech recognition. Younger normal-hearing (YNH), older normal-hearing (ONH), and older hearing-impaired (OHI) adults listened to sentences in noise that were spectrally shaped to control for individual hearing thresholds. A second YNH group listened to sentences with the same spectral shaping as OHI listeners. Sentence recognition generally improved with greater noise modulation depth, especially at higher modulation rates. Results suggest that speech recognition for all groups is maximized when speech modulations &amp;lt;8 Hz are preserved, when noise modulation occurs at rates higher than this range, and with greater noise modulation depth. OHI listeners benefit similarly from these conditions, but their poorer overall performance may be due to reduced sensation levels. [Work supported by NIH/NIDCD.]

Exploring the relationship between sound localization and individual use of spectral and temporal cues among hearing-impaired listeners

When locating a sound source, listeners are expected to rely more on spectral cues for elevation and temporal cues for azimuth. This work investigates whether sound localization ability can be predicted by individually-measured use of spectral and temporal cues. Participants were older adults with sensorineural hearing loss. Sound sources for the localization task were created in a virtual room, using a mix of virtual and physical loudspeakers in the front hemifield of the listener. Sources were distributed evenly between ±90 deg azimuth and ±20 deg elevation. The signal was a 1 s broadband 4-Hz amplitude-modulated noise. To assess the relationship between localization ability and use of spectral and temporal cues, listeners performed cue weighting and cue discrimination tasks. In the cue weighting task, listeners identified synthetic speech sounds that varied spectro-temporally. The cue discrimination task measured the smallest detectable difference in either spectral or temporal information among the same set of ambiguous speech sounds. Together, these tasks form a cue profile which identifies whether the listener relies to a greater extent on temporal or spectral cues. Older hearing-impaired listeners varied in their ability to localize sounds. Localization results will be discussed in the context of cue profiles and audiometry. [Work supported by NIH.]