Hearing-impaired Listeners Research Articles

Sequential auditory grouping reduces binaural pitch fusion in listeners with normal hearing, hearing aids, and cochlear implantsa).

Binaural pitch fusion, the perceptual integration of dichotically presented stimuli that evoke different pitches, can be considered a type of simultaneous grouping. Hence, auditory streaming cues such as temporally flanking stimuli that promote sequential grouping might compete with simultaneous dichotic grouping to reduce binaural fusion. Here, we measured binaural pitch fusion using an auditory streaming task in normal-hearing listeners and hearing-impaired listeners with hearing aids and/or cochlear implants. Fusion ranges, the frequency or electrode ranges over which binaural pitch fusion occurs, were measured in a streaming paradigm using 10 alterations of a dichotic reference/comparison stimulus with a diotic capture stimulus, with fusion indicated by perception of a single stream. Stimuli were pure tones or electric pulse trains depending on the hearing device, with frequency or electrode varied across trials for comparison stimuli. Fusion ranges were also measured for the corresponding isolated stimulus conditions with the same stimulus durations. For all groups, fusion ranges decreased by up to three times in the streaming paradigm compared to the corresponding isolated stimulus paradigm. Hearing-impaired listeners showed greater reductions in fusion than normal-hearing listeners. The findings add further evidence that binaural pitch fusion is moderated by central processes involved in auditory grouping or segregation.

Evaluating audio quality ratings and scene analysis performance of hearing-impaired listeners for multi-track music.

This study assessed musical scene analysis (MSA) performance and subjective quality ratings of multi-track mixes as a function of spectral manipulations using the EQ-transform (% EQT). This transform exaggerates or reduces the spectral shape changes in a given track with respect to a relatively flat, smooth reference spectrum. Data from 30 younger normal hearing (yNH) and 23 older hearing-impaired (oHI) participants showed that MSA performance was robust to changes in % EQT. However, audio quality ratings elicited from yNH participants were more sensitive to % EQT than those of oHI participants. A significant positive correlation between MSA performance and quality ratings among oHI showed that oHI participants with better MSA performances gave higher-quality ratings, whereas there was no significant correlation for yNH listeners. Overall, these data indicate the complementary virtue of measures of MSA and audio quality ratings for assessing the suitability of music mixes for hearing-impaired listeners.

Hearing Sensitivity to Gliding Rippled Spectra in Hearing-Impaired Listeners

Hearing Sensitivity to Gliding Rippled Spectra in Hearing-Impaired Listeners

Acoustic- Versus Intelligibility-Based Assessment of Subjective Listening Difficulty Measured With the Repeat-Recall Test

Objectives: To contrast interpretations of listening effort ratings when judged against acoustic- versus intelligibility-based normative references. Design: Existing data collected from 66 normal-hearing adult listeners, comprising 2730 trials of the Repeat-Recall Test, were used to establish norms of subjective listening effort ratings for six ranges of intelligibility. Data from 21 aided hearing-impaired listeners were then used to contrast intelligibility-based norms against acoustic-based norms when interpreting listening effort ratings measured in omnidirectional and directional microphone conditions. Results: Whereas acoustic-based norms effectively demonstrated reduced effort for directional versus omnidirectional microphone modes, intelligibility-based references controlled for listeners’ performance biases and improved the consistency with which subjective ratings were ranked across the two microphone conditions. Conclusions: The choice of normative reference should be carefully considered when judging listening effort ratings from hearing-impaired individuals against those of their normal-hearing peers. Whereas acoustic-based references may be more useful for evaluating the benefits of hearing aid technology, intelligibility-based references may be better suited to identifying listeners with poor subjective experiences for speech-in-noise related to factors beyond intelligibility.

The Audible Contrast Threshold (ACT) test: A clinical spectro-temporal modulation detection test

Over the last decade, multiple studies have shown that hearing-impaired listeners’ speech-in-noise reception ability, measured with audibility compensation, is closely associated with performance in spectro-temporal modulation (STM) detection tests. STM tests thus have the potential to provide highly relevant beyond-the-audiogram information in the clinic, but the available STM tests have not been optimized for clinical use in terms of test duration, required equipment, and procedural standardization. The present study introduces a quick-and-simple clinically viable STM test, named the Audible Contrast Threshold (ACT™) test. First, an experimenter-controlled STM measurement paradigm was developed, in which the patient is presented bilaterally with a continuous audibility-corrected noise via headphones and asked to press a pushbutton whenever they hear an STM target sound in the noise. The patient's threshold is established using a Hughson-Westlake tracking procedure with a three-out-of-five criterion and then refined by post-processing the collected data using a logistic function. Different stimulation paradigms were tested in 28 hearing-impaired participants and compared to data previously measured in the same participants with an established STM test paradigm. The best stimulation paradigm showed excellent test-retest reliability and good agreement with the established laboratory version. Second, the best stimulation paradigm with 1-second noise “waves” (windowed noise) was chosen, further optimized with respect to step size and logistic-function fitting, and tested in a population of 25 young normal-hearing participants using various types of transducers to obtain normative data. Based on these normative data, the “normalized Contrast Level” (in dB nCL) scale was defined, where 0 ± 4 dB nCL corresponds to normal performance and elevated dB nCL values indicate the degree of audible contrast loss. Overall, the results of the present study suggest that the ACT test may be considered a reliable, quick-and-simple (and thus clinically viable) test of STM sensitivity. The ACT can be measured directly after the audiogram using the same set up, adding only a few minutes to the process.

Horizontal Sound Localization and Spatial Short-Term Memory Span in Hearing-Impaired Listeners and Listeners With Simulated Hearing Loss.

Localization of a sound source in the horizontal plane depends on the listener's interaural comparison of arrival time and level. Hearing loss (HL) can reduce access to these binaural cues, possibly disrupting the localization and memory of spatial information. Thus, this study aimed to investigate the horizontal sound localization performance and the spatial short-term memory in listeners with actual and simulated HL. Seventeen listeners with bilateral symmetric HL and 17 listeners with normal hearing (NH) participated in the study. The hearing thresholds of NH listeners were elevated by a spectrally shaped masking noise for the simulations of unilateral hearing loss (UHL) and bilateral hearing loss (BHL). The localization accuracy and errors as well as the spatial short-term memory span were measured in the free field using a set of 11 loudspeakers arrayed over a 150° arc. The localization abilities and spatial short-term memory span did not significantly differ between actual BHL listeners and BHL-simulated NH listeners. Overall, the localization performance with the UHL simulation was approximately twofold worse than that with the BHL simulation, and the hearing asymmetry led to a detrimental effect on spatial memory. The mean localization score as a function of stimulus location in the UHL simulation was less than 30% even for the front (0° azimuth) stimuli and much worse on the side closer to the simulated ear. In the UHL simulation, the localization responses were biased toward the side of the intact ear even when sounds were coming from the front. Hearing asymmetry induced by the UHL simulation substantially disrupted the localization performance and recall abilities of spatial positions encoded and stored in the memory, due to fewer chances to learn strategies to improve localization. The marked effect of hearing asymmetry on sound localization highlights the need for clinical assessments of spatial hearing in addition to conventional hearing tests.

Subjective Speech Intelligibility Drives Noise-Tolerance Domain Use During the Tracking of Noise-Tolerance Test.

Recently, the Noise-Tolerance Domains Test (NTDT) was applied to study the noise-tolerance domains used by young normal-hearing (NH) listeners during noise acceptance decisions. In this study, we examined how subjective speech intelligibility may drive noise acceptance decisions by applying the NTDT on NH and hearing-impaired (HI) listeners at the signal to noise ratios (SNRs) around the Tracking of Noise-Tolerance (TNT) thresholds. A single-blind, within-subjects design with 22 NH and 17 HI older adults was followed. Listeners completed the TNT to determine the average noise acceptance threshold (TNTAve). Then, listeners completed the NTDT at the SNRs of 0, ±3 dB (re: TNTAve) to estimate the weighted noise-tolerance domain ratings (WNTDRs) for each domain criterion. Listeners also completed the Objective and Subjective Intelligibility Difference (OSID) Test to establish the individual intelligibility performance-intensity (P-I) functions of the TNT materials. All test measures were conducted at 75 and 82 dB SPL speech input levels. NH and HI listeners were tested in the unaided mode. The HI listeners were also tested using a study hearing aid. The WNTDRs were plotted against subjective speech intelligibilities extrapolated from individual P-I of the OSID at the SNRs corresponding to NTDT test conditions. Listeners were grouped according to their most heavily weighed domain and a regression analysis was performed against listener demographics as well as TNT and OSID performances to determine which variable(s) affected listener grouping. Three linear mixed effects (LMEs) models were used to examine whether WNTDRs changed with subjective speech intelligibility. All three LMEs found significant fixed effects of domain criteria, subjective intelligibility, and speech input level on WNTDRs. In general, heavier weights were assigned to speech interference and loudness domains at poorer intelligibility levels (<50%) with reversals to distraction and annoyance at higher intelligibility levels (>80%). The comparison between NH and HI-unaided showed that NH listeners assigned greater weights to loudness than the HI-unaided listeners. The comparison between NH and HI-aided groups showed similar weights between groups. The comparison between HI-unaided and HI-aided found that HI listeners assigned lower weights to speech interference and greater weights to loudness when tested in aided compared with unaided modes. In all comparisons, loudness was weighed heavier at the 82 dB SPL input level than at the 75 dB SPL input level with greater weights to annoyance in the NH versus HI-unaided comparison and lower weights to distraction in the HI-aided versus HI-unaided comparison. A generalized linear model determined that listener grouping was best accounted for by subjective speech intelligibility estimated at TNTAve. The domain criteria used by listeners were driven by their subjective speech intelligibility regardless of their hearing status (i.e., NH versus HI). In general, when subjective intelligibility was poor, the domains of speech interference and loudness were weighed the heaviest. As subjective intelligibility improved, the weightings on annoyance and distraction increased. Furthermore, a listener's criterion for >90% subjective speech understanding at the TNTAve may allow one to profile the listener.

The Optimal Speech-to-Background Ratio for Balancing Speech Recognition With Environmental Sound Recognition.

This study aimed to determine the speech-to-background ratios (SBRs) at which normal-hearing (NH) and hearing-impaired (HI) listeners can recognize both speech and environmental sounds when the two types of signals are mixed. Also examined were the effect of individual sounds on speech recognition and environmental sound recognition (ESR), and the impact of divided versus selective attention on these tasks. In Experiment 1 (divided attention), 11 NH and 10 HI listeners heard sentences mixed with environmental sounds at various SBRs and performed speech recognition and ESR tasks concurrently in each trial. In Experiment 2 (selective attention), 20 NH listeners performed these tasks in separate trials. Psychometric functions were generated for each task, listener group, and environmental sound. The range over which speech recognition and ESR were both high was determined, as was the optimal SBR for balancing recognition with ESR, defined as the point of intersection between each pair of normalized psychometric functions. The NH listeners achieved greater than 95% accuracy on concurrent speech recognition and ESR over an SBR range of approximately 20 dB or greater. The optimal SBR for maximizing both speech recognition and ESR for NH listeners was approximately +12 dB. For the HI listeners, the range over which 95% performance was observed on both tasks was far smaller (span of 1 dB), with an optimal value of +5 dB. Acoustic analyses indicated that the speech and environmental sound stimuli were similarly audible, regardless of the hearing status of the listener, but that the speech fluctuated more than the environmental sounds. Divided versus selective attention conditions produced differences in performance that were statistically significant yet only modest in magnitude. In all conditions and for both listener groups, recognition was higher for environmental sounds than for speech when presented at equal intensities (i.e., 0 dB SBR), indicating that the environmental sounds were more effective maskers of speech than the converse. Each of the 25 environmental sounds used in this study (with one exception) had a span of SBRs over which speech recognition and ESR were both higher than 95%. These ranges tended to overlap substantially. A range of SBRs exists over which speech and environmental sounds can be simultaneously recognized with high accuracy by NH and HI listeners, but this range is larger for NH listeners. The single optimal SBR for jointly maximizing speech recognition and ESR also differs between NH and HI listeners. The greater masking effectiveness of the environmental sounds relative to the speech may be related to the lower degree of fluctuation present in the environmental sounds as well as possibly task differences between speech recognition and ESR (open versus closed set). The observed differences between the NH and HI results may possibly be related to the HI listeners' smaller fluctuating masker benefit. As noise-reduction systems become increasingly effective, the current results could potentially guide the design of future systems that provide listeners with highly intelligible speech without depriving them of access to important environmental sounds.

The Intelligibility Benefits of Modern Computer-Synthesized Speech for Normal-Hearing and Hearing-Impaired Listeners in Non-Ideal Listening Conditions

The Intelligibility Benefits of Modern Computer-Synthesized Speech for Normal-Hearing and Hearing-Impaired Listeners in Non-Ideal Listening Conditions

Personalized prediction of speech intelligibility for hearing-impaired listeners using a physiological model of the human ear

Due to the problems of occlusion effect, insufficient high-frequency gain, and acoustic feedback in conventional hearing aids, middle ear implants as a new type of hearing device have become an important compensatory tool for the treatment of patients with moderate to severe hearing loss. However, current speech intelligibility (SI) models are inadequate for predicting SI in hearing-impaired (HI) listeners after middle ear implants implantation. Moreover, the compensatory performance of middle ear implants before implantation remains unknown due to the invasive nature of the surgical procedure. Therefore, this study proposes a novel SI model that can predict the compensatory effects on SI after middle ear implants implantation. The model combines a physiologically nonlinear auditory preprocessing front-end with a short-term correlation analysis back-end. In normal-hearing (NH) listeners, the model accurately predicts speech reception thresholds (SRTs) and masking release under steady-state and fluctuating noise conditions. For HI listeners, the model modifies the parameters of outer hair cells and inner hair cells in the preprocessing front-end to simulate the patient’s audiogram, achieving excellent predictive capability for HI listeners’ test data. Overall, the proposed SI model can be used for the optimal design and algorithm fitting of middle ear implants tailored to patients with varying degrees of hearing loss, offering valuable insights for the clinical treatment of HI listeners.

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.

Exploring perceptual segregation cues in polyphonic vocal music under normal and impaired hearing

Music plays an important role in the lives of many people, but its enjoyment can be compromised by hearing loss. Although the effects of hearing loss on speech are well-studied, its effects on music perception are less well-understood. This study examined normal-hearing and hearing-impaired listeners’ ability to hear out individual voices within polyphonic music, while varying the number of voices and the level of inharmonicity in each voice. We hypothesized that hearing loss would hinder listeners’ ability to distinguish voices in music due to impaired frequency selectivity and pitch perception but that inharmonicity would impact hearing-impaired listeners less, due to their reduced sensitivity to pitch discrepancies. MIDI-generated female vocal passages with one to five voices and different inharmonicity levels were presented in two tasks: estimating voice count (denumerability) and following a specific voice in the passage. Preliminary results indicate that hearing-impaired listeners struggle more with increasing voices than normal-hearing listeners but are less affected by inharmonicity. These outcomes align with our hypotheses, confirming that hearing loss leads to poorer overall performance and less sensitivity to inharmonicity. [Work supported by NIH grant R01DC005216.]

The theoretical maximum intelligibility improvement that can be provided by hearing aids

One goal of hearing aids is to increase the intelligibility of speech by improving the signal-to-noise ratio through the use of directional microphones and/or digital noise reduction. With this objective in mind, an ideal hearing aid would output amplified target speech with a signal-to-noise ratio of +∞. However, even in this ideal scenario, vent effects would allow background noise to enter the ear canal via the direct sound path while also allowing amplified sound to escape from the ear canal. In this experiment, a range of hearing aid fittings were simulated to account for these vent effects. Hearing-impaired listeners were tested using the ideal simulated hearing aid, and the results will show the maximum theoretical hearing aid benefit.

Processing of Visual Speech Cues in Speech-in-Noise Comprehension Depends on Working Memory Capacity and Enhances Neural Speech Tracking in Older Adults With Hearing Impairment.

Comprehending speech in noise (SiN) poses a challenge for older hearing-impaired listeners, requiring auditory and working memory resources. Visual speech cues provide additional sensory information supporting speech understanding, while the extent of such visual benefit is characterized by large variability, which might be accounted for by individual differences in working memory capacity (WMC). In the current study, we investigated behavioral and neurofunctional (i.e., neural speech tracking) correlates of auditory and audio-visual speech comprehension in babble noise and the associations with WMC. Healthy older adults with hearing impairment quantified by pure-tone hearing loss (threshold average: 31.85-57 dB, N = 67) listened to sentences in babble noise in audio-only, visual-only and audio-visual speech modality and performed a pattern matching and a comprehension task, while electroencephalography (EEG) was recorded. Behaviorally, no significant difference in task performance was observed across modalities. However, we did find a significant association between individual working memory capacity and task performance, suggesting a more complex interplay between audio-visual speech cues, working memory capacity and real-world listening tasks. Furthermore, we found that the visual speech presentation was accompanied by increased cortical tracking of the speech envelope, particularly in a right-hemispheric auditory topographical cluster. Post-hoc, we investigated the potential relationships between the behavioral performance and neural speech tracking but were not able to establish a significant association. Overall, our results show an increase in neurofunctional correlates of speech associated with congruent visual speech cues, specifically in a right auditory cluster, suggesting multisensory integration.

The effect of auditory training on listening effort in hearing-aid users: insights from a pupillometry study

Objective The study investigated how auditory training affects effort exerted by hearing-impaired listeners in speech-in-noise task. Design Pupillometry was used to characterise listening effort during a hearing in noise test (HINT) before and after phoneme-in-noise identification training. Half of the study participants completed the training, while the other half formed an active control group. Study sample Twenty 63-to-79 years old experienced hearing-aid users. Results Higher peak pupil dilations (PPDs) were obtained at the end of the study compared to the beginning in both groups of the participants. The analysis of pupil dilation in an extended time window revealed, however, that the magnitude of pupillary response increased more in the training than in the control group. The effect of training on effort was observed in pupil responses even when no improvement in HINT was found. Conclusion The results demonstrate that using a listening effort metric adds additional insights into the effectiveness of auditory training compared to the situation when only speech-in-noise performance is considered. Trends observed in pupil responses suggested increased effort—both after the training and the placebo intervention—most likely reflecting the effect of the individual’s motivation.

A spectro-temporal modulation test for predicting speech reception in hearing-impaired listeners with hearing aids

Spectro-temporal modulation (STM) detection sensitivity has been shown to be associated with speech-in-noise reception in hearing-impaired (HI) individuals. Based on previous research, a recent study [Zaar, Simonsen, Dau, and Laugesen (2023). Hear Res 427:108650] introduced an STM test paradigm with audibility compensation, employing STM stimulus variants using noise and complex tones as carrier signals. The study demonstrated that the test was suitable for the target population of elderly individuals with moderate-to-severe hearing loss and showed promising predictions of speech-reception thresholds (SRTs) measured in a realistic set up with spatially distributed speech and noise maskers and linear audibility compensation. The present study further investigated the suggested STM test with respect to (i) test-retest variability for the most promising STM stimulus variants, (ii) its predictive power with respect to realistic speech-in-noise reception with non-linear hearing-aid amplification, (iii) its connection to effects of directionality and noise reduction (DIR+NR) hearing-aid processing, and (iv) its relation to DIR+NR preference. Thirty elderly HI participants were tested in a combined laboratory and field study, collecting STM thresholds with a complex-tone based and a noise-based STM stimulus design, SRTs with spatially distributed speech and noise maskers using hearing aids with non-linear amplification and two different levels of DIR+NR, as well as subjective reports and preference ratings obtained in two field periods with the two DIR+NR hearing-aid settings. The results indicate that the noise-carrier based STM test variant (i) showed optimal test-retest properties, (ii) yielded a highly significant correlation with SRTs (R2=0.61) exceeding and complementing the predictive power of the audiogram, (iii) yielded significant correlation (R2=0.51) with the DIR+NR-induced SRT benefit, and (iv) did not provide significant correlation with subjective preference for DIR+NR settings in the field. Overall, the suggested STM test represents a valuable tool for diagnosing speech-reception problems that remain when hearing-aid amplification has been provided and the resulting need for and benefit from DIR+NR hearing-aid processing.

Fusion of dichotic consonants in normal-hearing and hearing-impaired listenersa).

Hearing-impaired (HI) listeners have been shown to exhibit increased fusion of dichotic vowels, even with different fundamental frequency (F0), leading to binaural spectral averaging and interference. To determine if similar fusion and averaging occurs for consonants, four natural and synthesized stop consonants (/pa/, /ba/, /ka/, /ga/) at three F0s of 74, 106, and 185 Hz were presented dichotically-with ΔF0 varied-to normal-hearing (NH) and HI listeners. Listeners identified the one or two consonants perceived, and response options included /ta/ and /da/ as fused percepts. As ΔF0 increased, both groups showed decreases in fusion and increases in percent correct identification of both consonants, with HI listeners displaying similar fusion but poorer identification. Both groups exhibited spectral averaging (psychoacoustic fusion) of place of articulation but phonetic feature fusion for differences in voicing. With synthetic consonants, NH subjects showed increased fusion and decreased identification. Most HI listeners were unable to discriminate the synthetic consonants. The findings suggest smaller differences between groups in consonant fusion than vowel fusion, possibly due to the presence of more cues for segregation in natural speech or reduced reliance on spectral cues for consonant perception. The inability of HI listeners to discriminate synthetic consonants suggests a reliance on cues other than formant transitions for consonant discrimination.

Automated Measurement of Speech Recognition, Reaction Time, and Speech Rate and Their Relation to Self-Reported Listening Effort for Normal-Hearing and Hearing-Impaired Listeners Using various Maskers.

In speech audiometry, the speech-recognition threshold (SRT) is usually established by adjusting the signal-to-noise ratio (SNR) until 50% of the words or sentences are repeated correctly. However, these conditions are rarely encountered in everyday situations. Therefore, for a group of 15 young participants with normal hearing and a group of 12 older participants with hearing impairment, speech-recognition scores were determined at SRT and at four higher SNRs using several stationary and fluctuating maskers. Participants' verbal responses were recorded, and participants were asked to self-report their listening effort on a categorical scale (self-reported listening effort, SR-LE). The responses were analyzed using an Automatic Speech Recognizer (ASR) and compared to the results of a human examiner. An intraclass correlation coefficient of r = .993 for the agreement between their corresponding speech-recognition scores was observed. As expected, speech-recognition scores increased with increasing SNR and decreased with increasing SR-LE. However, differences between speech-recognition scores for fluctuating and stationary maskers were observed as a function of SNR, but not as a function of SR-LE. The verbal response time (VRT) and the response speech rate (RSR) of the listeners' responses were measured using an ASR. The participants with hearing impairment showed significantly lower RSRs and higher VRTs compared to the participants with normal hearing. These differences may be attributed to differences in age, hearing, or both. With increasing SR-LE, VRT increased and RSR decreased. The results show the possibility of deriving a behavioral measure, VRT, measured directly from participants' verbal responses during speech audiometry, as a proxy for SR-LE.

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.

Effective Duration of Auditory Training for Speech Perception in Hearing-Impaired Listeners: A Systematic Review and Meta-Analysis

Purpose: The purpose of this study was to conduct a meta-analysis to determine the effective duration of auditory training for hearing aid users and cochlear implant users and to identify factors that influence the effectiveness of auditory training.Methods: We searched literature published from January 1996 to August 2021 in Pubmed, Web of Science, Embase and Cochrane Library. A total of 24 studies that met the selection criteria were systematically reviewed and analyzed through meta-analysis. Standardized mean differences and 95% confidence intervals were calculated.Results: The overall meta-analysis results for auditory training showed an effect size of -0.833, and the effect size was larger in “more than 600 minutes of auditory training” compared to “less than 600 minutes”. There was no statistically significant difference in effect size during follow-up observation after the completion of auditory training, with an effect size of 0.057 (95% CI: -0.113-0.112, &lt;i&gt;p&lt;/i&gt;=0.988). Subgroup analysis showed that the effect size was larger in the “children” group than in the “adult” group. The effect size of auditory training was larger when the auditory training and measurement conditions were the same.Conclusions: Auditory training can improve speech perception in individuals wearing HA and/or CI, and the training effect was shown to be maintained even after the completion of auditory training. In addition, it was found that the longer the duration of auditory training (more than 10 hours), the greater the training effect.