Listening effort and fatigue in school-age children with and without hearing loss

Role of Active Listening and Listening Effort on Contralateral Suppression of Transient Evoked Otoacousic Emissions

Background and Objectives

The present study aimed to investigate the effect of active listening and listening effort on the contralateral suppression of transient evoked otoacoustic emissions (CSTEOAEs).

Subjects and Methods

Twenty eight young adults participated in the study. Transient evoked otoacoustic emissions (TEOAEs) were recorded using ‘linear’ clicks at 60 dB peSPL, in three contralateral noise conditions. In condition 1, TEOAEs were obtained in the presence of white noise in the contralateral ear. While, in condition 2, speech was embedded into white noise at +3, −3, and −9 dB signal-to-noise ratio (SNR) and delivered to the contralateral ear. The SNR was varied to investigate the effect of listening effort on the CSTEOAE. In condition 3, speech was played backwards and embedded into white noise at −3 dB SNR. The conditions 1 and 3 served as passive listening condition and the condition 2 served as active listening condition. In active listening condition, the participants categorized the words in to two groups (e.g., animal and vehicle).

Results

CSTEOAE was found to be largest in the presence of white noise, and the amount of CSTEOAE was not significantly different between active and passive listening conditions (condition 2 and 3). Listening effort had an effect on the CSTEOAE, the amount of suppression increased with listening effort, when SNR was decreased from +3 dB to −3 dB. However, when the SNR was further reduced to −9 dB, there was no further increase in the amount of CSTEOAE, instead there was a reduction in the amount of suppression.

Conclusions

The findings of the present study show that listening effort might affect CSTEOAE.

Impact of cognition and noise reduction on speech perception in adults with unilateral cochlear implants

OBJECTIVES

The purpose of this study was to investigate the impact of cognition and noise reduction (NR) technology in cochlear implants (CIs) on speech perception and listening effort.

METHODS

Thirteen adults fitted with unilateral CIs (Nucleus^® 6, CP900) participated in this study. Participants performed: (I) cognitive tests of working memory and processing speed, (II) speech perception in noise tests, and (III) an auditory-visual dual-task paradigm to quantify listening effort, as a part of the three-phase experimental study. Both the participant and the tester, performing the outcome measures, were blinded to the NR settings (ON/OFF) of the CI for phases II and III.

RESULTS

Speech intelligibility significantly improved with the NR activated, but was independent of individual differences in cognitive abilities. Listening effort did not significantly change with NR setting; however, there was a trend for participants with good working memory to have better speech perception scores with NR activated during the effortful listening task (dual-task paradigm).

CONCLUSION

Future studies are warranted to explore the interaction between cognition and CI NR algorithms during an effortful listening task.

Neurodynamic evaluation of hearing aid features using EEG correlates of listening effort

In this study, we propose a novel estimate of listening effort using electroencephalographic data. This method is a translation of our past findings, gained from the evoked electroencephalographic activity, to the oscillatory EEG activity. To test this technique, electroencephalographic data from experienced hearing aid users with moderate hearing loss were recorded, wearing hearing aids. The investigated hearing aid settings were: a directional microphone combined with a noise reduction algorithm in a medium and a strong setting, the noise reduction setting turned off, and a setting using omnidirectional microphones without any noise reduction. The results suggest that the electroencephalographic estimate of listening effort seems to be a useful tool to map the exerted effort of the participants. In addition, the results indicate that a directional processing mode can reduce the listening effort in multitalker listening situations.

Effort Not Speed Characterizes Comprehension of Spoken Sentences by Older Adults with Mild Hearing Impairment

In spite of the rapidity of everyday speech, older adults tend to keep up relatively well in day-to-day listening. In laboratory settings older adults do not respond as quickly as younger adults in off-line tests of sentence comprehension, but the question is whether comprehension itself is actually slower. Two unique features of the human eye were used to address this question. First, we tracked eye-movements as 20 young adults and 20 healthy older adults listened to sentences that referred to one of four objects pictured on a computer screen. Although the older adults took longer to indicate the referenced object with a cursor-pointing response, their gaze moved to the correct object as rapidly as that of the younger adults. Second, we concurrently measured dilation of the pupil of the eye as a physiological index of effort. This measure revealed that although poorer hearing acuity did not slow processing, success came at the cost of greater processing effort.

The Effects of Directional Processing on Objective and Subjective Listening Effort

PURPOSE

The purposes of this investigation were (a) to evaluate the effects of hearing aid directional processing on subjective and objective listening effort and (b) to investigate the potential relationships between subjective and objective measures of effort.

METHOD

Sixteen adults with mild to severe hearing loss were tested with study hearing aids programmed with 3 settings: omnidirectional, fixed directional, and bilateral beamformer. A dual-task paradigm and subjective ratings were used to assess objective and subjective listening effort, respectively, in 2 signal-to-noise ratios. Testing occurred in rooms with either low or moderate reverberation.

RESULTS

Directional processing improved subjective and objective listening effort, although benefit for objective effort was found only in moderate reverberation. Subjective reports of work and tiredness were more highly correlated with word recognition performance than objective listening effort. However, subjective ratings about control were significantly correlated with objective listening effort.

CONCLUSIONS

Directional microphone technology in hearing aids has the potential to improve listening effort in moderately reverberant environments. In addition, subjective questions that probe a listener's desire to exercise control may be a viable method for eliciting ratings that are significantly related to objective listening effort.

Multitasking During Degraded Speech Recognition in School-Age Children

Multitasking requires individuals to allocate their cognitive resources across different tasks. The purpose of the current study was to assess school-age children's multitasking abilities during degraded speech recognition. Children (8 to 12 years old) completed a dual-task paradigm including a sentence recognition (primary) task containing speech that was either unprocessed or noise-band vocoded with 8, 6, or 4 spectral channels and a visual monitoring (secondary) task. Children's accuracy and reaction time on the visual monitoring task was quantified during the dual-task paradigm in each condition of the primary task and compared with single-task performance. Children experienced dual-task costs in the 6- and 4-channel conditions of the primary speech recognition task with decreased accuracy on the visual monitoring task relative to baseline performance. In all conditions, children's dual-task performance on the visual monitoring task was strongly predicted by their single-task (baseline) performance on the task. Results suggest that children's proficiency with the secondary task contributes to the magnitude of dual-task costs while multitasking during degraded speech recognition.

Cognitive Compensation of Speech Perception With Hearing Impairment, Cochlear Implants, and Aging

External degradations in incoming speech reduce understanding, and hearing impairment further compounds the problem. While cognitive mechanisms alleviate some of the difficulties, their effectiveness may change with age. In our research, reviewed here, we investigated cognitive compensation with hearing impairment, cochlear implants, and aging, via (a) phonemic restoration as a measure of top-down filling of missing speech, (b) listening effort and response times as a measure of increased cognitive processing, and (c) visual world paradigm and eye gazing as a measure of the use of context and its time course. Our results indicate that between speech degradations and their cognitive compensation, there is a fine balance that seems to vary greatly across individuals. Hearing impairment or inadequate hearing device settings may limit compensation benefits. Cochlear implants seem to allow the effective use of sentential context, but likely at the cost of delayed processing. Linguistic and lexical knowledge, which play an important role in compensation, may be successfully employed in advanced age, as some compensatory mechanisms seem to be preserved. These findings indicate that cognitive compensation in hearing impairment can be highly complicated—not always absent, but also not easily predicted by speech intelligibility tests only.

Rapid Release From Listening Effort Resulting From Semantic Context, and Effects of Spectral Degradation and Cochlear Implants

People with hearing impairment are thought to rely heavily on context to compensate for reduced audibility. Here, we explore the resulting cost of this compensatory behavior, in terms of effort and the efficiency of ongoing predictive language processing. The listening task featured predictable or unpredictable sentences, and participants included people with cochlear implants as well as people with normal hearing who heard full-spectrum/unprocessed or vocoded speech. The crucial metric was the growth of the pupillary response and the reduction of this response for predictable versus unpredictable sentences, which would suggest reduced cognitive load resulting from predictive processing. Semantic context led to rapid reduction of listening effort for people with normal hearing; the reductions were observed well before the offset of the stimuli. Effort reduction was slightly delayed for people with cochlear implants and considerably more delayed for normal-hearing listeners exposed to spectrally degraded noise-vocoded signals; this pattern of results was maintained even when intelligibility was perfect. Results suggest that speed of sentence processing can still be disrupted, and exertion of effort can be elevated, even when intelligibility remains high. We discuss implications for experimental and clinical assessment of speech recognition, in which good performance can arise because of cognitive processes that occur after a stimulus, during a period of silence. Because silent gaps are not common in continuous flowing speech, the cognitive/linguistic restorative processes observed after sentences in such studies might not be available to listeners in everyday conversations, meaning that speech recognition in conventional tests might overestimate sentence-processing capability.

Subjective Listening Effort and Electrodermal Activity in Listening Situations with Reverberation and Noise

Disturbing factors like reverberation or ambient noise can impair speech recognition and raise the listening effort needed for successful communication in daily life. Situations with high listening effort are thought to result in increased stress for the listener. The aim of this study was to explore possible measures to determine listening effort in situations with varying background noise and reverberation. For this purpose, subjective ratings of listening effort, speech recognition, and stress level, together with the electrodermal activity as a measure of the autonomic stress reaction, were investigated. It was expected that the electrodermal activity would show different stress levels in different acoustic situations and might serve as an alternative to subjective ratings. Ten young normal-hearing and 17 elderly hearing-impaired subjects listened to sentences from the Oldenburg sentence test either with stationary background noise or with reverberation. Four listening situations were generated, an easy and a hard one for each of the two disturbing factors, which were related to each other by the Speech Transmission Index. The easy situation resulted in 100% and the hard situation resulted in 30 to 80% speech recognition. The results of the subjective ratings showed significant differences between the easy and the hard listening situations in both subject groups. Two methods of analyzing the electrodermal activity values revealed similar, but nonsignificant trends. Significant correlations between subjective ratings and physiological electrodermal activity data were observed for normal-hearing subjects in the noise situation.

Effects of Noise on Speech Recognition and Listening Effort in Children With Normal Hearing and Children With Mild Bilateral or Unilateral Hearing Loss

PURPOSE

This study examined the effects of stimulus type and hearing status on speech recognition and listening effort in children with normal hearing (NH) and children with mild bilateral hearing loss (MBHL) or unilateral hearing loss (UHL).

METHOD

Children (5-12 years of age) with NH (Experiment 1) and children (8-12 years of age) with MBHL, UHL, or NH (Experiment 2) performed consonant identification and word and sentence recognition in background noise. Percentage correct performance and verbal response time (VRT) were assessed (onset time, total duration).

RESULTS

In general, speech recognition improved as signal-to-noise ratio (SNR) increased both for children with NH and children with MBHL or UHL. The groups did not differ on measures of VRT. Onset times were longer for incorrect than for correct responses. For correct responses only, there was a general increase in VRT with decreasing SNR.

CONCLUSIONS

Findings indicate poorer sentence recognition in children with NH and MBHL or UHL as SNR decreases. VRT results suggest that greater effort was expended when processing stimuli that were incorrectly identified. Increasing VRT with decreasing SNR for correct responses also supports greater effort in poorer acoustic conditions. The absence of significant hearing status differences suggests that VRT was not differentially affected by MBHL, UHL, or NH for children in this study.

The Effects of Meaning-Based Auditory Training on Behavioral Measures of Perceptual Effort in Individuals with Impaired Hearing

There has been considerable interest in measuring the perceptual effort required to understand speech, as well as to identify factors that might reduce such effort. In the current study, we investigated whether, in addition to improving speech intelligibility, auditory training also could reduce perceptual or listening effort. Perceptual effort was assessed using a modified version of the n-back memory task in which participants heard lists of words presented without background noise and were asked to continually update their memory of the three most recently presented words. Perceptual effort was indexed by memory for items in the three-back position immediately before, immediately after, and 3 months after participants completed the Computerized Learning Exercises for Aural Rehabilitation (clEAR), a 12-session computerized auditory training program. Immediate posttraining measures of perceptual effort indicated that participants could remember approximately one additional word compared to pretraining. Moreover, some training gains were retained at the 3-month follow-up, as indicated by significantly greater recall for the three-back item at the 3-month measurement than at pretest. There was a small but significant correlation between gains in intelligibility and gains in perceptual effort. The findings are discussed within the framework of a limited-capacity speech perception system.

Minimal Hearing Loss: From a Failure-Based Approach to Evidence-Based Practice

PURPOSE

A representative sample of the literature on minimal hearing loss (MHL) was reviewed to provide evidence of challenges faced by children with MHL and to establish the need for evidence-based options for early intervention.

METHOD

Research articles published from 1950 to 2013 were searched in the Medline database using the keywords minimal hearing loss, unilateral hearing loss, and mild hearing loss. References cited in retrieved articles were also reviewed.

RESULTS

In total, 69 articles contained relevant information about pediatric outcomes and/or intervention for unilateral hearing loss, 50 for mild hearing loss, and 6 for high-frequency hearing loss. Six challenges associated with MHL emerged, and 6 interventions were indicated. Evidence indicates that although some individuals may appear to have no observable speech-language or academic difficulties, others experience considerable difficulties. It also indicates that even though children with MHL may appear to catch up in some areas, difficulties in select domains continue into adulthood.

CONCLUSIONS

Evidence indicates significant risks associated with untreated MHL. Evidence also demonstrates the need for early intervention and identifies several appropriate intervention strategies; however, no single protocol is appropriate for all children. Therefore, families should be educated about the impact of MHL and about available interventions so that informed decisions can be made.

Impact of Hearing Aid Technology on Outcomes in Daily Life II: Speech Understanding and Listening Effort

OBJECTIVES

Modern hearing aid (HA) devices include a collection of acoustic signal-processing features designed to improve listening outcomes in a variety of daily auditory environments. Manufacturers market these features at successive levels of technological sophistication. The features included in costlier premium hearing devices are designed to result in further improvements to daily listening outcomes compared with the features included in basic hearing devices. However, independent research has not substantiated such improvements. This research was designed to explore differences in speech-understanding and listening-effort outcomes for older adults using premium-feature and basic-feature HAs in their daily lives.

DESIGN

For this participant-blinded, repeated, crossover trial 45 older adults (mean age 70.3 years) with mild-to-moderate sensorineural hearing loss wore each of four pairs of bilaterally fitted HAs for 1 month. HAs were premium- and basic-feature devices from two major brands. After each 1-month trial, participants' speech-understanding and listening-effort outcomes were evaluated in the laboratory and in daily life.

RESULTS

Three types of speech-understanding and listening-effort data were collected: measures of laboratory performance, responses to standardized self-report questionnaires, and participant diary entries about daily communication. The only statistically significant superiority for the premium-feature HAs occurred for listening effort in the loud laboratory condition and was demonstrated for only one of the tested brands.

CONCLUSIONS

The predominant complaint of older adults with mild-to-moderate hearing impairment is difficulty understanding speech in various settings. The combined results of all the outcome measures used in this research suggest that, when fitted using scientifically based practices, both premium- and basic-feature HAs are capable of providing considerable, but essentially equivalent, improvements to speech understanding and listening effort in daily life for this population. For HA providers to make evidence-based recommendations to their clientele with hearing impairment it is essential that further independent research investigates the relative benefit/deficit of different levels of hearing technology across brands and manufacturers in these and other real-world listening domains.

Known-Groups and Concurrent Validity of the Mandarin Tone Identification Test (MTIT)

Objective

The Mandarin Tone Identification Test (MTIT) is a new test designed to assess the tone identification abilities of children with hearing impairment (HI). Evidence for reliability and sensitivity has been reported. The present study aimed to evaluate the known-groups and concurrent validity of the MTIT.

Design

The MTIT and Mandarin Pediatric Speech Intelligibility test (MPSI) were administered in quiet and in noise conditions. The known-groups validity was evaluated by comparing the performance of the MTIT on children with two different levels of HI. The MPSI was included to evaluate the concurrent validity of the MTIT.

Study sample

81 children with HI were recruited in the present study. They were Mandarin-speaking children with profound HI (mean age = 9; 0, n = 41) and with moderate to severe HI (mean age = 8; 9, n = 40).

Results

Scores on the MTIT differed between the two groups with different hearing levels suggesting good known-groups validity. A strong relationship between tone and sentence perception both in quiet and in noise provided preliminary evidence for concurrent validity.

Conclusions

The present study confirmed that the MTIT has good known-groups validity and provided preliminary evidence for concurrent validity. The MTIT could be used to evaluate tone identification ability in children with HI with confidence.

Assessing speech perception in children with hearing loss: what conventional clinical tools may miss

OBJECTIVES

This study tested the hypothesis that word recognition in a complex, two-talker masker is more closely related to real-world speech perception for children with hearing loss than testing performed in quiet or steady-state noise.

DESIGN

Sixteen school-age hearing aid users were tested on aided word recognition in noise or two-talker speech. Unaided estimates of speech perception in quiet were retrospectively obtained from the clinical record. Ten parents completed a questionnaire regarding their children's ease of communication and understanding in background noise.

RESULTS

Unaided performance in quiet was correlated with aided performance in competing noise, but not in two-talker speech. Only results in the two-talker masker were correlated with parental reports of their children's functional hearing abilities.

CONCLUSIONS

Speech perception testing in a complex background such as two-talker speech may provide a more accurate predictor of the communication challenges of children with hearing loss than testing in steady noise or quiet.

Cochlear implantation in adults with unilateral deafness: A review of the assessment/evaluation protocols

OBJECTIVES

Cochlear implantation is becoming widely used outside the tertiary research centers for treatment of unilateral deafness (UD). No consensus exists, however, on the most suitable assessment/evaluation protocols for this group of adult patients. This paper aims to review the assessment and evaluation protocols used by various research groups and to propose a protocol for the use in the clinical setting.

METHODS

The PubMed, Embase, and Cochrane Library databases were searched with the keywords 'cochlear', 'implant', 'single-sided', 'deafness', 'adults', 'unilateral', and 'deafness'. The words were either used individually, combined in pairs, or in groups of 5. All articles reporting on prospective studies, retrospective studies, or case studies were included.

RESULTS

Sixteen published studies met the inclusion criteria. Measures of hearing performance, tinnitus, subjective quality of hearing, and quality of life varied greatly among studies.

DISCUSSION

Adaptive speech in noise testing, localization, tinnitus measurement questionnaires, and self-rated hearing improvement are widely used among the research groups. These tools in conjunction assess and evaluate the main issues associated with UD.

CONCLUSION

The test battery most commonly used to assess and evaluate adult cochlea implant users with UD consists of (a) a subjective self-rating of hearing performance, (b) localization testing, and

Sensitive periods and language in cochlear implant users

This study explores the hypothesis that the existence of a short sensitive period for lower-level speech perception/articulation skills, and a long one for higher-level language skills, may partly explain the language outcomes of children with cochlear implants (CIs). The participants were fourteen children fitted with a CI before their second birthday. Data about their language skills and the environmental conditions (e.g. Family Involvement in rehabilitation) were obtained over a period of three years. Age at implantation correlated exclusively with the ratio of errors of place of articulation, a phonological feature for which CIs provide insufficient information. The degree of Family Involvement was significantly correlated with the remaining language measures. We conclude that small plasticity reductions affecting lower-level skills may partly explain the difficulties of some CI users in developing language.

Parasympathetic Nervous System Dysfunction, as Identified by Pupil Light Reflex, and Its Possible Connection to Hearing Impairment

CONTEXT

Although the pupil light reflex has been widely used as a clinical diagnostic tool for autonomic nervous system dysfunction, there is no systematic review available to summarize the evidence that the pupil light reflex is a sensitive method to detect parasympathetic dysfunction. Meanwhile, the relationship between parasympathetic functioning and hearing impairment is relatively unknown.

OBJECTIVES

To 1) review the evidence for the pupil light reflex being a sensitive method to evaluate parasympathetic dysfunction, 2) review the evidence relating hearing impairment and parasympathetic activity and 3) seek evidence of possible connections between hearing impairment and the pupil light reflex.

METHODS

Literature searches were performed in five electronic databases. All selected articles were categorized into three sections: pupil light reflex and parasympathetic dysfunction, hearing impairment and parasympathetic activity, pupil light reflex and hearing impairment.

RESULTS

Thirty-eight articles were included in this review. Among them, 36 articles addressed the pupil light reflex and parasympathetic dysfunction. We summarized the information in these data according to different types of parasympathetic-related diseases. Most of the studies showed a difference on at least one pupil light reflex parameter between patients and healthy controls. Two articles discussed the relationship between hearing impairment and parasympathetic activity. Both studies reported a reduced parasympathetic activity in the hearing impaired groups. The searches identified no results for pupil light reflex and hearing impairment.

DISCUSSION AND CONCLUSIONS

As the first systematic review of the evidence, our findings suggest that the pupil light reflex is a sensitive tool to assess the presence of parasympathetic dysfunction. Maximum constriction velocity and relative constriction amplitude appear to be the most sensitive parameters. There are only two studies investigating the relationship between parasympathetic activity and hearing impairment, hence further research is needed. The pupil light reflex could be a candidate measurement tool to achieve this goal.

Autonomic Nervous System Responses During Perception of Masked Speech may Reflect Constructs other than Subjective Listening Effort

Typically, understanding speech seems effortless and automatic. However, a variety of factors may, independently or interactively, make listening more effortful. Physiological measures may help to distinguish between the application of different cognitive mechanisms whose operation is perceived as effortful. In the present study, physiological and behavioral measures associated with task demand were collected along with behavioral measures of performance while participants listened to and repeated sentences. The goal was to measure psychophysiological reactivity associated with three degraded listening conditions, each of which differed in terms of the source of the difficulty (distortion, energetic masking, and informational masking), and therefore were expected to engage different cognitive mechanisms. These conditions were chosen to be matched for overall performance (keywords correct), and were compared to listening to unmasked speech produced by a natural voice. The three degraded conditions were: (1) Unmasked speech produced by a computer speech synthesizer, (2) Speech produced by a natural voice and masked byspeech-shaped noise and (3) Speech produced by a natural voice and masked by two-talker babble. Masked conditions were both presented at a -8 dB signal to noise ratio (SNR), a level shown in previous research to result in comparable levels of performance for these stimuli and maskers. Performance was measured in terms of proportion of key words identified correctly, and task demand or effort was quantified subjectively by self-report. Measures of psychophysiological reactivity included electrodermal (skin conductance) response frequency and amplitude, blood pulse amplitude and pulse rate. Results suggest that the two masked conditions evoked stronger psychophysiological reactivity than did the two unmasked conditions even when behavioral measures of listening performance and listeners’ subjective perception of task demand were comparable across the three degraded conditions.

The Effects of Noise and Reverberation on Listening Effort in Adults With Normal Hearing

OBJECTIVES

The purpose of this study was to investigate the effects of background noise and reverberation on listening effort. Four specific research questions were addressed related to listening effort: (A) With comparable word recognition performance across levels of reverberation, what are the effects of noise and reverberation on listening effort? (B) What is the effect of background noise when reverberation time is constant? (C) What is the effect of increasing reverberation from low to moderate when signal to noise ratio is constant? (D) What is the effect of increasing reverberation from moderate to high when signal to noise ratio is constant?

DESIGN

Eighteen young adults (mean age 24.8 years) with normal hearing participated. A dual-task paradigm was used to simultaneously assess word recognition and listening effort. The primary task was monosyllable word recognition, and the secondary task was word categorization (press a button if the word heard was judged to be a noun). Participants were tested in quiet and in background noise in three levels of reverberation (T30 < 100 ms, T30 = 475 ms, and T30 = 834 ms). Signal to noise ratios used were chosen individually for each participant and varied by reverberation to address the specific research questions.

RESULTS

As expected, word recognition performance was negatively affected by both background noise and by increases in reverberation. Furthermore, analysis of mean response times revealed that background noise increased listening effort, regardless of degree of reverberation. Conversely, reverberation did not affect listening effort, regardless of whether word recognition performance was comparable or signal to noise ratio was constant.

CONCLUSIONS

The finding that reverberation did not affect listening effort, even when word recognition performance was degraded, is inconsistent with current models of listening effort. The reasons for this surprising finding are unclear and warrant further investigation. However, the results of this study are limited in generalizability to young listeners with normal hearing and to the signal to noise ratios, loudspeaker to listener distance, and reverberation times evaluated. Other populations, like children, older listeners, and listeners with hearing loss, have been previously shown to be more sensitive to reverberation. Therefore, the effects of reverberation for these vulnerable populations also warrant further investigation.

Delay in auditory behaviour and preverbal vocalization in infants with unilateral hearing loss

AIM

To evaluate the impact of unilateral hearing loss (UHL) on early aural/oral communication skills of infants by comparing performance to infants with bilateral normal hearing (BNH).

METHOD

Thirty-four infants with UHL (median age 9.4mo, 25th-75th centile 7.34-12.15) and 331 control infants with BNH (median age 9mo, 6.0-13.38) were divided into two subgroups based on risk factors known to cause developmental delay: low risk and high risk. Early auditory skills and preverbal vocalizations were assessed using two parent questionnaires: the Infant-Toddler Meaningful Auditory Integration Scale and the Production of Infants Scale Evaluation.

RESULTS

Of the infants with UHL, 21% showed delays in auditory behaviour and 41% delays in preverbal vocalizations, compared to their peers with BNH (p<0.01). After adjusting for risk level, delayed auditory behaviour and preverbal vocalizations were approximately four and nine times more common in infants with UHL compared to BNH respectively (p<0.01).

INTERPRETATION

This is the first study to show that infants with UHL are at higher risk of delay in early aural/oral communication abilities compared to infants with BNH even in the absence of other known risk factors for developmental delay. This has important implications for early intervention and habilitation of infants with UHL, in order to reduce some of the negative long-term consequences of what was once considered 'minor' hearing loss.

Comparison of Psychophysiological and Dual-Task Measures of Listening Effort

PURPOSE

We wished to make a comparison of psychophysiological measures of listening effort with subjective and dual-task measures of listening effort for a diotic-dichotic-digits and a sentences-in-noise task.

METHOD

Three groups of young adults (18-38 years old) with normal hearing participated in three experiments: two psychophysiological studies for two different listening tasks and a dual-task measure for a sentences-in-noise task. Psychophysiological variables included skin conductance, heart-rate variability, and heart rate; the dual-task measure was a letter-identification task. Heart-rate variability was quantified with the difference from baseline for the normalized standard deviation of R to R.

RESULTS

Heart-rate variability differences from baseline were greater for increased task complexity and for poorer signal-to-noise ratios (SNRs). The dual-task measure of listening effort also increased for sentences presented at a +5 dB SNR compared with a +15 dB SNR. Skin conductance was elevated for greater task complexity only, and similar across noise conditions. None of these measures were significantly correlated with subjective measures of listening effort.

CONCLUSIONS

Heart-rate variability appears to be a robust psychophysiological indicator of listening effort, sensitive to both task complexity and SNR. This sensitivity to SNR was similar to a dual-task measure of listening effort.

Evaluation of wideband frequency responses and non-linear frequency compression for children with mild to moderate high-frequency hearing loss

OBJECTIVE

To evaluate wideband amplification and non-linear frequency compression (NLFC) as a means to improve speech recognition for children with mild/moderate hearing loss.

DESIGN

Randomized within-subject design with repeated measures across test conditions.

STUDY SAMPLE

Eleven children with mild to moderate hearing loss were evaluated with: (1) Phonak BTE without NLFC, (2) Phonak BTE with NLFC, and (3) Oticon BTE with wideband response extending to 8000 Hz.

RESULTS

Use of NLFC provided better detection and recognition of high-frequency stimuli (e.g. /sh/ and /s/). No difference in performance between conditions was observed for speech recognition when measured with the University of Western Ontario (UWO) plurals test and the UWO distinctive features difference test. Finally, there were no differences between conditions on the BKB-SIN test.

CONCLUSIONS

Children with mild to moderate hearing loss have good access to high-frequency phonemes presented at fixed levels (e.g. 50 to 60 dBA) with both wideband and NLFC technology. Similarly, sentence recognition in noise was similar with wideband and NLFC. Adaptive test procedures that probe performance at lower input levels showed small but significant improvements in the detection and recognition of the phonemes /s/ and /sh/ with NLFC condition when compared to the NLFC Off and wideband conditions.

Amblyaudia: Review of Pathophysiology, Clinical Presentation, and Treatment of a New Diagnosis

OBJECTIVE

Similar to amblyopia in the visual system, "amblyaudia" is a term used to describe persistent hearing difficulty experienced by individuals with a history of asymmetric hearing loss (AHL) during a critical window of brain development. Few clinical reports have described this phenomenon and its consequent effects on central auditory processing. We aim to (1) define the concept of amblyaudia and (2) review contemporary research on its pathophysiology and emerging clinical relevance.

DATA SOURCES

PubMed, Embase, and Cochrane databases.

REVIEW METHODS

A systematic literature search was performed with combinations of search terms: "amblyaudia," "conductive hearing loss," "sensorineural hearing loss," "asymmetric," "pediatric," "auditory deprivation," and "auditory development." Relevant articles were considered for inclusion, including basic and clinical studies, case series, and major reviews.

CONCLUSIONS

During critical periods of infant brain development, imbalanced auditory input associated with AHL may lead to abnormalities in binaural processing. Patients with amblyaudia can demonstrate long-term deficits in auditory perception even with correction or resolution of AHL. The greatest impact is in sound localization and hearing in noisy environments, both of which rely on bilateral auditory cues. Diagnosis and quantification of amblyaudia remain controversial and poorly defined. Prevention of amblyaudia may be possible through early identification and timely management of reversible causes of AHL.

IMPLICATIONS FOR PRACTICE

Otolaryngologists, audiologists, and pediatricians should be aware of emerging data supporting amblyaudia as a diagnostic entity and be cognizant of the potential for lasting consequences of AHL. Prevention of long-term auditory deficits may be possible through rapid identification and correction.

The Effect of Age on Listening Effort

PURPOSE

The objective of this study was to investigate the effect of age on listening effort.

METHOD

A dual-task paradigm was used to evaluate listening effort in different conditions of background noise. Sixty adults ranging in age from 20 to 77 years were included. A primary speech-recognition task and a secondary memory task were performed both separately and simultaneously. Multiple regression analyses were used to evaluate how age and hearing thresholds affect speech recognition and listening effort scores.

RESULTS

Results of the multiple regression analyses showed that age is a significant determinant of listening effort, whereby listening effort increases with increasing age even when age-related variance in speech recognition is partialled out. On the basis of the regression equations and the median score for listening effort, it was found that listening effort started to increase in the fourth decade of life.

CONCLUSIONS

This study was a first exploration of listening effort from young to older adults and showed that, independent of hearing sensitivity, listening effort increases with age. To be more specific, there is a need to further investigate the cognitive functions important for speech communication while exploring their possible relationship with listening effort.

Listening efficiency during lessons under various types of noise

Pupils inside primary school classrooms can be exposed to extraneous noise, impairing their performance in the speech reception process. The different noises show a peculiar impact, depending on their level, spectral content and temporal fine structure. In order to understand how the disturbance is built up over time, in this work a large data set was analyzed, detailing the changes of pupils' performance as the lesson progresses from the start to the end. Several types of noise are considered (traffic, tapping and activity noise) and the analysis concerns III to V graders of the Italian primary school (8 to 10 year old pupils). By using as indicators the intelligibility scores, the response time and their ratio, the so-called "listening efficiency," several findings are achieved. Pupils respond differently to each noise during the course of the lesson. In the better listening conditions, the performance in the speech reception worsens under traffic and babble noise whereas an opposite trend is found under tapping noise. On the contrary adaptation is observed in the worse listening conditions for the traffic noise alone. Moreover, indications are achieved that the age proficiency may affect differently babble noise compared to traffic and tapping noise.

A review of causal mechanisms underlying the link between age-related hearing loss and cognitive decline

Accumulating evidence points to a link between age-related hearing loss and cognitive decline, but their relationship is not clear. Does one cause the other, or does some third factor produce both? The answer has critical implications for prevention, rehabilitation, and health policy but has been difficult to establish for several reasons. First, determining a causal relationship in natural, correlational samples is problematic, and hearing and cognition are difficult to measure independently. Here, we critically review the evidence for a link between hearing loss and cognitive decline. We conclude that the evidence is convincing, but that the effects are small when hearing is measured audiometrically. We review four different directional hypotheses that have been offered as explanations for such a link, and conclude that no single hypothesis is sufficient. We introduce a framework that highlights that hearing and cognition rely on shared neurocognitive resources, and relate to each other in several different ways. We also discuss interventions for sensory and cognitive decline that may permit more causal inferences.

A Comparison of Two Methods for Measuring Listening Effort As Part of an Audiologic Test Battery

PURPOSE

We evaluated 2 measures of listening effort (a self-report measure and a word recall measure) regarding their suitability for inclusion in a comprehensive audiologic testing protocol. The relationship between the 2 measures was explored, and both measures were examined with regard to validity, sensitivity, and effect on speech intelligibility performance.

METHOD

Thirty adults with normal hearing participated. Speech intelligibility performance was evaluated at 4 signal-to-noise ratios by using keywords embedded in both high- and low-context sentences. Listening effort was evaluated at set intervals throughout the speech intelligibility task.

RESULTS

Results obtained with the 2 measures were consistent with expected changes in listening effort. However, data obtained with the self-report method demonstrated greater sensitivity to these changes. The 2 measures were uncorrelated. Under certain conditions, speech intelligibility performance was more negatively affected when the word recall measure was used. Exploration of additional theoretical and practical considerations supported a conclusion that the self-report measure was preferable for measuring listening effort simultaneously with speech intelligibility.

CONCLUSION

The results of this study provide a rationale for preferring the self-report measure of listening effort over the word recall measure when testing audiologic outcomes.

Commentary: listening can be exhausting--fatigue in children and adults with hearing loss

Anecdotal reports of fatigue after sustained speech-processing demands are common among adults with hearing loss; however, systematic research examining hearing loss-related fatigue is limited, particularly with regard to fatigue among children with hearing loss (CHL). Many audiologists, educators, and parents have long suspected that CHL experience stress and fatigue as a result of the difficult listening demands they encounter throughout the day at school. Recent research in this area provides support for these intuitive suggestions. In this article, the authors provide a framework for understanding the construct of fatigue and its relation to hearing loss, particularly in children. Although empirical evidence is limited, preliminary data from recent studies suggest that some CHL experience significant fatigue-and such fatigue has the potential to compromise a child's performance in the classroom. In this commentary, the authors discuss several aspects of fatigue including its importance, definitions, prevalence, consequences, and potential linkage to increased listening effort in persons with hearing loss. The authors also provide a brief synopsis of subjective and objective methods to quantify listening effort and fatigue. Finally, the authors suggest a common-sense approach for identification of fatigue in CHL; and, the authors briefly comment on the use of amplification as a management strategy for reducing hearing-related fatigue.

Measuring listening effort: driving simulator versus simple dual-task paradigm

OBJECTIVES

The dual-task paradigm has been widely used to measure listening effort. The primary objectives of the study were to (1) investigate the effect of hearing aid amplification and a hearing aid directional technology on listening effort measured by a complicated, more real world dual-task paradigm and (2) compare the results obtained with this paradigm to a simpler laboratory-style dual-task paradigm.

DESIGN

The listening effort of adults with hearing impairment was measured using two dual-task paradigms, wherein participants performed a speech recognition task simultaneously with either a driving task in a simulator or a visual reaction-time task in a sound-treated booth. The speech materials and road noises for the speech recognition task were recorded in a van traveling on the highway in three hearing aid conditions: unaided, aided with omnidirectional processing (OMNI), and aided with directional processing (DIR). The change in the driving task or the visual reaction-time task performance across the conditions quantified the change in listening effort.

RESULTS

Compared to the driving-only condition, driving performance declined significantly with the addition of the speech recognition task. Although the speech recognition score was higher in the OMNI and DIR conditions than in the unaided condition, driving performance was similar across these three conditions, suggesting that listening effort was not affected by amplification and directional processing. Results from the simple dual-task paradigm showed a similar trend: hearing aid technologies improved speech recognition performance, but did not affect performance in the visual reaction-time task (i.e., reduce listening effort). The correlation between listening effort measured using the driving paradigm and the visual reaction-time task paradigm was significant. The finding showing that our older (56 to 85 years old) participants' better speech recognition performance did not result in reduced listening effort was not consistent with literature that evaluated younger (approximately 20 years old), normal hearing adults. Because of this, a follow-up study was conducted. In the follow-up study, the visual reaction-time dual-task experiment using the same speech materials and road noises was repeated on younger adults with normal hearing. Contrary to findings with older participants, the results indicated that the directional technology significantly improved performance in both speech recognition and visual reaction-time tasks.

CONCLUSIONS

Adding a speech listening task to driving undermined driving performance. Hearing aid technologies significantly improved speech recognition while driving, but did not significantly reduce listening effort. Listening effort measured by dual-task experiments using a simulated real-world driving task and a conventional laboratory-style task was generally consistent. For a given listening environment, the benefit of hearing aid technologies on listening effort measured from younger adults with normal hearing may not be fully translated to older listeners with hearing impairment.

Subjective fatigue in children with hearing loss: some preliminary findings

PURPOSE

In this study, the authors examined the effect of hearing loss on subjective reports of fatigue in school-age children using a standardized measure.

METHODS

As part of a larger ongoing study, the authors obtained subjective ratings of fatigue using the Pediatric Quality of Life Inventory (PedsQL) Multidimensional Fatigue Scale ( Varni, Burwinkle, Katz, Meeske, & Dickinson, 2002). This standardized scale provides a measure of general fatigue, sleep/rest fatigue, cognitive fatigue, and an overall composite measure of fatigue. To date, data from 10 children with hearing loss (CHL) and 10 age-matched children with normal hearing (CNH) have been analyzed.

RESULTS

These preliminary results show that subjective fatigue is increased in school-age children with hearing loss (Cohen's d = 0.78-1.90). In addition, the impact of hearing loss on fatigue in school-age children appears pervasive across multiple domains (general, sleep/rest, and cognitive fatigue).

CONCLUSION

School-age CHL reported significantly more fatigue than did CNH. These preliminary data are important given the negative academic and psychosocial consequences associated with fatigue. Further research is needed to determine the underlying mechanisms responsible for this increased fatigue in school-age children with hearing loss, and to identify factors that may modulate (e.g., degree of loss) and mediate (e.g., hearing aid or cochlear implant use) its impact.

On the interaction of speakers' voice quality, ambient noise and task complexity with children's listening comprehension and cognition

Suboptimal listening conditions interfere with listeners’ on-line comprehension. A degraded source signal, noise that interferes with sound transmission, and/or listeners’ cognitive or linguistic limitations are examples of adverse listening conditions. Few studies have explored the interaction of these factors in pediatric populations. Yet, they represent an increasing challenge in educational settings. We will in the following report on our research and address the effect of adverse listening conditions pertaining to speakers’ voices, background noise, and children’s cognitive capacity on listening comprehension. Results from our studies clearly indicate that children risk underachieving both in formal assessments and in noisy class-rooms when an examiner or teacher speaks with a hoarse (dysphonic) voice. This seems particularly true when task complexity is low or when a child is approaching her/his limits of mastering a comprehension task.

Spatial release of cognitive load measured in a dual-task paradigm in normal-hearing and hearing-impaired listeners

This study investigated whether spatial separation between talkers helps reduce cognitive processing load, and how hearing impairment interacts with the cognitive load of individuals listening in multi-talker environments. A dual-task paradigm was used in which performance on a secondary task (visual tracking) served as a measure of the cognitive load imposed by a speech recognition task. Visual tracking performance was measured under four conditions in which the target and the interferers were distinguished by (1) gender and spatial location, (2) gender only, (3) spatial location only, and (4) neither gender nor spatial location. Results showed that when gender cues were available, a 15° spatial separation between talkers reduced the cognitive load of listening even though it did not provide further improvement in speech recognition (Experiment I). Compared to normal-hearing listeners, large individual variability in spatial release of cognitive load was observed among hearing-impaired listeners. Cognitive load was lower when talkers were spatially separated by 60° than when talkers were of different genders, even though speech recognition was comparable in these two conditions (Experiment II). These results suggest that a measure of cognitive load might provide valuable insight into the benefit of spatial cues in multi-talker environments.

Binaural fusion and listening effort in children who use bilateral cochlear implants: a psychoacoustic and pupillometric study

Bilateral cochlear implants aim to provide hearing to both ears for children who are deaf and promote binaural/spatial hearing. Benefits are limited by mismatched devices and unilaterally-driven development which could compromise the normal integration of left and right ear input. We thus asked whether children hear a fused image (ie. 1 vs 2 sounds) from their bilateral implants and if this “binaural fusion” reduces listening effort. Binaural fusion was assessed by asking 25 deaf children with cochlear implants and 24 peers with normal hearing whether they heard one or two sounds when listening to bilaterally presented acoustic click-trains/electric pulses (250 Hz trains of 36 ms presented at 1 Hz). Reaction times and pupillary changes were recorded simultaneously to measure listening effort. Bilaterally implanted children heard one image of bilateral input less frequently than normal hearing peers, particularly when intensity levels on each side were balanced. Binaural fusion declined as brainstem asymmetries increased and age at implantation decreased. Children implanted later had access to acoustic input prior to implantation due to progressive deterioration of hearing. Increases in both pupil diameter and reaction time occurred as perception of binaural fusion decreased. Results indicate that, without binaural level cues, children have difficulty fusing input from their bilateral implants to perceive one sound which costs them increased listening effort. Brainstem asymmetries exacerbate this issue. By contrast, later implantation, reflecting longer access to bilateral acoustic hearing, may have supported development of auditory pathways underlying binaural fusion. Improved integration of bilateral cochlear implant signals for children is required to improve their binaural hearing.

Effect of minimal/mild hearing loss on children's speech understanding in a simulated classroom

OBJECTIVES

While classroom acoustics can affect educational performance for all students, the impact for children with minimal/mild hearing loss (MMHL) may be greater than for children with normal hearing (NH). The purpose of this study was to examine the effect of MMHL on children's speech recognition comprehension and looking behavior in a simulated classroom environment. It was hypothesized that children with MMHL would perform similarly to their peers with NH on the speech recognition task but would perform more poorly on the comprehension task. Children with MMHL also were expected to look toward talkers more often than children with NH.

DESIGN

Eighteen children with MMHL and 18 age-matched children with NH participated. In a simulated classroom environment, children listened to lines from an elementary-age-appropriate play read by a teacher and four students reproduced over LCD monitors and loudspeakers located around the listener. A gyroscopic headtracking device was used to monitor looking behavior during the task. At the end of the play, comprehension was assessed by asking a series of 18 factual questions. Children also were asked to repeat 50 meaningful sentences with three key words each presented audio-only by a single talker either from the loudspeaker at 0 degree azimuth or randomly from the five loudspeakers.

RESULTS

Both children with NH and those with MMHL performed at or near ceiling on the sentence recognition task. For the comprehension task, children with MMHL performed more poorly than those with NH. Assessment of looking behavior indicated that both groups of children looked at talkers while they were speaking less than 50% of the time. In addition, the pattern of overall looking behaviors suggested that, compared with older children with NH, a larger portion of older children with MMHL may demonstrate looking behaviors similar to younger children with or without MMHL.

CONCLUSIONS

The results of this study demonstrate that, under realistic acoustic conditions, it is difficult to differentiate performance among children with MMHL and children with NH using a sentence recognition task. The more cognitively demanding comprehension task identified performance differences between these two groups. The comprehension task represented a condition in which the persons talking change rapidly and are not readily visible to the listener. Examination of looking behavior suggested that, in this complex task, attempting to visualize the talker may inefficiently utilize cognitive resources that would otherwise be allocated for comprehension.

Listening effort and speech intelligibility in listening situations affected by noise and reverberation

This study compared the combined effect of noise and reverberation on listening effort and speech intelligibility to predictions of the speech transmission index (STI). Listening effort was measured in normal-hearing subjects using a scaling procedure. Speech intelligibility scores were measured in the same subjects and conditions: (a) Speech-shaped noise as the only interfering factor, (b) + (c) fixed signal-to-noise ratios (SNRs) of 0 or 7 dB and reverberation as detrimental factors, and (d) reverberation as the only detrimental factor. In each condition, SNR and reverberation were combined to produce STI values of 0.17, 0.30, 0.43, 0.57, and 0.70, respectively. Listening effort always decreased with increasing STI, thus enabling a rough prediction, but a significant bias was observed indicating that listening effort was lower in reverberation only than in noise only at the same STI for one type of impulse responses. Accordingly, speech intelligibility increased with increasing STI and was significantly better in reverberation only than in noise only at the same STI. Further analyses showed that the broadband reverberation time is not always a good estimate of speech degradation in reverberation and that different speech materials may differ in their robustness toward detrimental effects of reverberation.

Listening effort and perceived clarity for normal-hearing children with the use of digital noise reduction

OBJECTIVES

The goal of this study was to evaluate how digital noise reduction (DNR) impacts listening effort and judgment of sound clarity in children with normal hearing. It was hypothesized that when two DNR algorithms differing in signal-to-noise ratio (SNR) output are compared, the algorithm that provides the greatest improvement in overall output SNR will reduce listening effort and receive a better clarity rating from child listeners. A secondary goal was to evaluate the relation between the inversion method measurements and listening effort with DNR processing.

DESIGN

Twenty-four children with normal hearing (ages 7 to 12 years) participated in a speech recognition task in which consonant-vowel-consonant nonwords were presented in broadband background noise. Test stimuli were recorded through two hearing aids with DNR off and DNR on at 0 dB and +5 dB input SNR. Stimuli were presented to listeners and verbal response time (VRT) and phoneme recognition scores were measured. The underlying assumption was that an increase in VRT reflects an increase in listening effort. Children rated the sound clarity for each condition. The two commercially available HAs were chosen based on: (1) an inversion technique, which was used to quantify the magnitude of change in SNR with the activation of DNR, and (2) a measure of magnitude-squared coherence, which was used to ensure that DNR in both devices preserved the spectrum.

RESULTS

One device provided a greater improvement in overall output SNR than the other. Both DNR algorithms resulted in minimal spectral distortion as measured using coherence. For both devices, VRT decreased for the DNR-on condition, suggesting that listening effort decreased with DNR in both devices. Clarity ratings were also better in the DNR-on condition for both devices. The device showing the greatest improvement in output SNR with DNR engaged improved phoneme recognition scores. The magnitude of this improved phoneme recognition was not accurately predicted with measurements of output SNR. Measured output SNR varied in the ability to predict other outcomes.

CONCLUSIONS

Overall, results suggest that DNR effectively reduces listening effort and improves subjective clarity ratings in children with normal hearing but that these improvements are not necessarily related to the output SNR improvements or preserved speech spectra provided by the DNR.

Can mild bilateral sensorineural hearing loss affect developmental abilities in younger school-age children?

The research study was conducted for the purpose of examining the influence of mild bilateral sensorineural hearing loss (MBSNHL) on developmental abilities of younger school-age children. The sample encompassed 144 children with MBSNHL, aged 7.5-11 (M = 8.85). MBSNHL (20-40 dB HL) was identified by pure tone audiometry. The control group encompassed 160 children with normal hearing. The Acadia test of developmental abilities was used for assessment of developmental abilities. Although statistically significant differences between participants with MBSNHL and those with normal hearing were established in the majority of estimated developmental abilities domains, those differences do not indicate any significant delay in development of assessed abilities, except in the domain of auditory discrimination. The obtained results call for a systematic approach to children with MBSNHL in elementary schools.

Children with Minimal/Mild Hearing Loss: Do We Have a Consensus and is that Important?

Children with minimal/mild hearing loss make up approximately 5% of the school-age population. While there is considerable research indicating that these children experience difficulties in a number of areas, there also is research indicating that they perform similarly to their peers with normal hearing. Understanding the potential difficulties that these children may experience and how their communication access needs may differ from those of their peers with normal hearing is important for habilitation. A lack of clear consensus could negatively impact provision of habilitation services. Awareness of factors that may affect that consensus can be useful in interpreting findings. This paper will address a number of those potential factors.

The Complexities of Fatigue in Children with Hearing Loss

Fatigue is a common phenomenon in our society, and it can have a major impact on an individual's performance and wellbeing. Parents and teachers have long believed that children with hearing loss (CHL) are at increased risk for fatigue. One could easily speculate that toward the end of a school day, CHL may be “physically and mentally spent” as a result of focusing so intently on a teacher's speech, as well as conversations with other students. Moreover, the increased listening effort, stress, and subsequent fatigue experienced by CHL could jeopardize the ability to learn in a noisy classroom environment, thus increasing the risk for problems in school. Only recently, however, have we begun to see empirical studies supporting the notion that CHL experience more fatigue than children with normal hearing (CNH).

This review was developed to enhance the awareness of fatigue among those audiologists interested in serving CHL. To this end, we have presented an overview on fatigue in CHL, including its importance, definitions, prevalence, consequences, and recent developments. The complexity and multifaceted nature of fatigue has been highlighted and the need for additional research on fatigue in CHL is emphasized.

Speech-perception training for older adults with hearing loss impacts word recognition and effort

The current pupillometry study examined the impact of speech-perception training on word recognition and cognitive effort in older adults with hearing loss. Trainees identified more words at the follow-up than at the baseline session. Training also resulted in an overall larger and faster peaking pupillary response, even when controlling for performance and reaction time. Perceptual and cognitive capacities affected the peak amplitude of the pupil response across participants but did not diminish the impact of training on the other pupil metrics. Thus, we demonstrated that pupillometry can be used to characterize training-related and individual differences in effort during a challenging listening task. Importantly, the results indicate that speech-perception training not only affects overall word recognition, but also a physiological metric of cognitive effort, which has the potential to be a biomarker of hearing loss intervention outcome.