Combining Cardiovascular and Pupil Features Using k-Nearest Neighbor Classifiers to Assess Task Demand, Social Context, and Sentence Accuracy During Listening.

In daily life, both acoustic factors and social context can affect listening effort investment. In laboratory settings, information about listening effort has been deduced from pupil and cardiovascular responses independently. The extent to which these measures can jointly predict listening-related factors is unknown. Here we combined pupil and cardiovascular features to predict acoustic and contextual aspects of speech perception. Data were collected from 29 adults (mean  =  64.6 years, SD  =  9.2) with hearing loss. Participants performed a speech perception task at two individualized signal-to-noise ratios (corresponding to 50% and 80% of sentences correct) and in two social contexts (the presence and absence of two observers). Seven features were extracted per trial: baseline pupil size, peak pupil dilation, mean pupil dilation, interbeat interval, blood volume pulse amplitude, pre-ejection period and pulse arrival time. These features were used to train k-nearest neighbor classifiers to predict task demand, social context and sentence accuracy. The k-fold cross validation on the group-level data revealed above-chance classification accuracies: task demand, 64.4%; social context, 78.3%; and sentence accuracy, 55.1%. However, classification accuracies diminished when the classifiers were trained and tested on data from different participants. Individually trained classifiers (one per participant) performed better than group-level classifiers: 71.7% (SD  =  10.2) for task demand, 88.0% (SD  =  7.5) for social context, and 60.0% (SD  =  13.1) for sentence accuracy. We demonstrated that classifiers trained on group-level physiological data to predict aspects of speech perception generalized poorly to novel participants. Individually calibrated classifiers hold more promise for future applications.

Exploring Factors That Contribute to the Success of Rehabilitation With Hearing Aids.

OBJECTIVES: Hearing aids are an essential and important part of hearing rehabilitation. The combination of technical data on hearing aids and individual rehabilitation needs can give insight into the factors that contribute to the success of rehabilitation. This study sets out to investigate if different subgroups of (comparable) hearing aids lead to differences in the success of rehabilitation, and whether these differences vary between different domains of auditory functioning. DESIGN: This study explored the advantages of including patient-reported outcome measures (PROMs) in the process of purchasing new hearing aids in a large sample of successful hearing aid users. Subject data were obtained from 64 (commercial) hearing aid dispensers and 10 (noncommercial) audiological centers in the Netherlands. The PROM was a 32-item questionnaire and was used to determine the success of rehabilitation using hearing aids by measuring auditory disability over time. The items were mapped on six domains of auditory functioning: detection, discrimination, localization, speech in quiet, speech in noise, and noise tolerance, encompassing a variety of daily-life listening situations. Hearing aids were grouped by means of cluster analysis, resulting in nine subgroups. In total, 1149 subjects were included in this study. A general linear model was used to model the final PROM results. Model results were analyzed via a multifactor Analysis of Variance. Post hoc analyses provided detailed information on model variables. RESULTS: Results showed a strong statistically significant effect of hearing aids on self-perceived auditory functioning in general. Clinically relevant differences were found for auditory domains including detection, speech in quiet, speech in noise, and localization. There was only a small, but significant, effect of the different subgroups of hearing aids on the final PROM results, where no differences were found between the auditory domains. Minor differences were found between results obtained in commercial and noncommercial settings, or between novice and experienced users. Severity of Hearing loss, age, gender, and hearing aid style (i.e., behind-the-ear versus receiver-in-canal type) did not have a clinically relevant effect on the final PROM results. CONCLUSIONS: The use of hearing aids has a large positive effect on self-perceived auditory functioning. There was however no salient effect of the different subgroups of hearing aids on the final PROM results, indicating that technical properties of hearing aids only play a limited role in this respect. This study challenges the belief that premium devices outperform basic ones, highlighting the need for personalized rehabilitation strategies and the importance of evaluating factors contributing to successful rehabilitation for clinical practice.

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

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

Copresence Was Found to Be Related to Some Pupil Measures in Persons With Hearing Loss While They Performed a Speech-in-Noise Task.

OBJECTIVES: To assess if a manipulation of copresence was related to speech-in-noise task performance, arousal, and effort of persons with hearing loss. Task-related arousal and effort were measured by means of pupillometry. DESIGN: Twenty-nine participants (mean age: 64.6 years) with hearing loss (4-frequency pure-tone average [4F-PTA] of 50.2 dB HL [SD = 8.9 dB] in the right ear and 51.3 dB HL [SD = 8.7 dB] in the left ear; averaged across 0.5, 1, 2, and 4 kHz) listened to and repeated spoken Danish sentences that were masked by four streams of continuous speech. Participants were presented with blocks of 20 sentences, during which copresence was manipulated by having participants do the task either alone or accompanied by two observers who were recruited from a similar age group. The task was presented at two difficulty levels, which was accomplished by fixing the signal-to-noise ratio of the speech and masker to match the thresholds at which participants were estimated to correctly repeat 50% (difficult) or 80% (easy) of the sentences in a block. Performance was assessed based on whether or not sentences were repeated correctly. Measures of pupil size (baseline pupil size [BPS], peak pupil dilation [PPD], and mean pupil dilation [MPD]) were used to index arousal and effort. Participants also completed ratings of subjective effort and stress after each block of sentences and a self-efficacy for listening-questionnaire. RESULTS: Task performance was not associated with copresence, but was found to be related to 4F-PTA. An increase in BPS was found for copresence conditions, compared to alone conditions. Furthermore, a post-hoc exploratory analysis revealed that the copresence conditions were associated with a significantly larger pupil size in the second half of the task-evoked pupil response (TEPR). No change in PPD or MPD did was detected between copresence and alone conditions. Self-efficacy, 4F-PTA, and age were not found to be related to the pupil data. Subjective ratings were sensitive to task difficulty but not copresence. CONCLUSION: Copresence was not found to be related to speech-in-noise performance, PPD, or MPD in persons with HL but was associated with an increase in arousal (as indicated by a larger BPS). This could be related to premobilization of effort and/or discomfort in response to the observers' presence. Furthermore, an exploratory analysis of the pupil data showed that copresence was associated with greater pupil dilations in the second half of the TEPR. This may indicate that participants invested more effort during the speech-in-noise task while in the presence of the observers, but that this increase in effort may not necessarily have been related to listening itself. Instead, other speech-in-noise task-related processes, such as preparing to respond, could have been influenced by copresence.

The Effects of Tinnitus and Tinnitus Annoyance on Need for Recovery After Work: Results of the Netherlands Longitudinal Study on Hearing.

OBJECTIVES: The first aim of this study was to examine the relationship between having tinnitus and the need for recovery after work (NFR). The second aim was to investigate whether the level of tinnitus annoyance is associated with NFR. DESIGN: Data from the 5- and 10-year follow-up measurement rounds of the Netherlands Longitudinal Study on Hearing (NL-SH) were used in a cross-sectional analyses. The NL-SH is a web-based prospective cohort study and includes participants aged 18 to 70 years at baseline. For this study, we included only participants who worked at least 12 hours/week and were under the age of 65 years. Participants completed questionnaires on demographic, socioeconomic, psychosocial, hearing-related, and work-related characteristics. In addition, participants answered questions about hearing ability and tinnitus and performed an online digit-triplet speech recognition in noise test to measure the speech reception threshold (SRT) in noise. Participants were asked if (1) they suffer from tinnitus and (2) to rate tinnitus annoyance on a 0-100 numeric rating scale. A linear mixed model was used (1) to estimate the overall (i.e., cross-sectional) association between having tinnitus and NFR and (2) to estimate the overall association between the level of tinnitus annoyance and NFR. The models were checked for effect modification and confounding of factors known to be associated with either tinnitus or NFR and available in the NL-SH. RESULTS: The study sample comprised 770 unique participants in total; 686 and 335 participants at 5- and 10-year follow-up, respectively. Distress, somatization, and self-reported hearing disability appeared to be confounding factors in the analysis of having tinnitus and NFR. After adjusting for these factors, participants with tinnitus had a 2.5% higher NFR (95% confidence interval: -0.9 to 5.9; p = 0.15). In the analysis of tinnitus annoyance and NFR, SRT was an effect modifier. Distress, somatization, depression, and self-reported hearing disability were confounders. After adjustment for effect modification and confounding, tinnitus annoyance was not significantly associated with NFR ( p = 0.79 for tinnitus annoyance). CONCLUSIONS: This study showed that having tinnitus was not associated with a higher NFR. Also, higher levels of tinnitus annoyance were not associated with a higher NFR. NFR was associated with the psychological factors distress, somatization, and depression, which are known to be intricately related to tinnitus. A longitudinal study design is recommended as it can assess the sequence of events, which might help disentangle the association between tinnitus, NFR, and psychological factors.

Informational masking with speech-on-speech intelligibility: Pupil response and time-course of learning.

Previous research has shown a learning effect on speech perception in nonstationary maskers. The present study addressed the time-course of this learning effect and the role of informational masking. To that end, speech reception thresholds (SRTs) were measured for speech in either a stationary noise masker, an interrupted noise masker, or a single-talker masker. The utterance of the single talker was either time-forward (intelligible) or time-reversed (unintelligible), and the sample of the utterance was either frozen (same utterance at each presentation) or random (different utterance at each presentation but from the same speaker). Simultaneously, the pupil dilation response was measured to assess differences in the listening effort between conditions and to track changes in the listening effort over time within each condition. The results showed a learning effect for all conditions but the stationary noise condition-that is, improvement in SRT over time while maintaining equal pupil responses. There were no significant differences in pupil responses between conditions despite large differences in the SRT. Time reversal of the frozen speech affected neither the SRT nor pupil responses.

The Presence of Another Individual Influences Listening Effort, But Not Performance.

OBJECTIVES: The aim of this study was to modify a speech perception in noise test to assess whether the presence of another individual (copresence), relative to being alone, affected listening performance and effort expenditure. Furthermore, this study assessed if the effect of the other individual's presence on listening effort was influenced by the difficulty of the task and whether participants had to repeat the sentences they listened to or not. DESIGN: Thirty-four young, normal-hearing participants (mean age: 24.7 years) listened to spoken Dutch sentences that were masked with a stationary noise masker and presented through a loudspeaker. The participants alternated between repeating sentences (active condition) and not repeating sentences (passive condition). They did this either alone or together with another participant in the booth. When together, participants took turns repeating sentences. The speech-in-noise test was performed adaptively at three intelligibility levels (20%, 50%, and 80% sentences correct) in a block-wise fashion. During testing, pupil size was recorded as an objective outcome measure of listening effort. RESULTS: Lower speech intelligibility levels were associated with increased peak pupil dilation (PPDs) and doing the task in the presence of another individual (compared with doing it alone) significantly increased PPD. No interaction effect between intelligibility and copresence on PPD was found. The results suggested that the change of PPD between doing the task alone or together was especially apparent for people who started the experiment in the presence of another individual. Furthermore, PPD was significantly lower during passive listening, compared with active listening. Finally, it seemed that performance was unaffected by copresence. CONCLUSION: The increased PPDs during listening in the presence of another participant suggest that more effort was invested during the task. However, it seems that the additional effort did not result in a change of performance. This study showed that at least one aspect of the social context of a listening situation (in this case copresence) can affect listening effort, indicating that social context might be important to consider in future cognitive hearing research.

The Influence of Hearing Loss on Cognitive Control in an Auditory Conflict Task: Behavioral and Pupillometry Findings.

Purpose The pupil dilation response is sensitive not only to auditory task demand but also to cognitive conflict. Conflict is induced by incompatible trials in auditory Stroop tasks in which participants have to identify the presentation location (left or right ear) of the words "left" or "right." Previous studies demonstrated that the compatibility effect is reduced if the trial is preceded by another incompatible trial (conflict adaptation). Here, we investigated the influence of hearing status on cognitive conflict and conflict adaptation in an auditory Stroop task. Method Two age-matched groups consisting of 32 normal-hearing participants (M age = 52 years, age range: 25-67 years) and 28 participants with hearing impairment (M age = 52 years, age range: 23-64 years) performed an auditory Stroop task. We assessed the effects of hearing status and stimulus compatibility on reaction times (RTs) and pupil dilation responses. We furthermore analyzed the Pearson correlation coefficients between age, degree of hearing loss, and the compatibility effects on the RT and pupil response data across all participants. Results As expected, the RTs were longer and pupil dilation was larger for incompatible relative to compatible trials. Furthermore, these effects were reduced for trials following incompatible (as compared to compatible) trials (conflict adaptation). No general effect of hearing status was observed, but the correlations suggested that higher age and a larger degree of hearing loss were associated with more interference of current incompatibility on RTs. Conclusions Conflict processing and adaptation effects were observed on the RTs and pupil dilation responses in an auditory Stroop task. No general effects of hearing status were observed, but the correlations suggested that higher age and a greater degree of hearing loss were related to reduced conflict processing ability. The current study underlines the relevance of taking into account cognitive control and conflict adaptation processes.

Please try harder! The influence of hearing status and evaluative feedback during listening on the pupil dilation response, saliva-cortisol and saliva alpha-amylase levels.

The pupil dilation response is sensitive both to listening effort and the emotional significance of a task. We aimed to assess the influence of evaluative feedback on the pupil dilation response using a speech reception threshold (SRT) task. Besides the pupil dilation response, we acquired subjective ratings and two physiological biomarkers sensitive to stress: cortisol and alpha-amylase levels as determined in saliva samples. We included 34 participants with normal hearing (mean age = 52 years, age range 25-67 years) and 29 age-matched participants with mild-to-moderate hearing loss (mean age = 52 years, age range 23-64 years). Half of the participants performed a standard SRT test without feedback, and the other half performed an SRT test in which they did receive feedback and were urged to perform better. The SRT conditions targeted 50% and 71% correct reception of the sentences. Pupil size was recorded and saliva samples were obtained and participants rated their experience of the task. Participants with hearing loss performed more poorly on the SRT test than participants with normal hearing participants receiving feedback had better SRTs in the 71% intelligibility condition and higher peak pupil dilation in both intelligibility conditions than participants who did not receive feedback, irrespective of hearing status. Saliva cortisol level and alpha-amylase activity reflected the usual diurnal patterns but showed no effects of hearing status or feedback. Finally, participants who received feedback experienced more difficulties than those who did not receive feedback, irrespective of hearing status. This study underlines the importance of taking into account the influence of task instructions and feedback in a speech perception task as these factors may influence the experienced difficulties, listening effort, and task performance.

Effect of Audibility and Suprathreshold Deficits on Speech Recognition for Listeners With Unilateral Hearing Loss.

OBJECTIVES: We examined the influence of impaired processing (audibility and suprathreshold processes) on speech recognition in cases of sensorineural hearing loss. The influence of differences in central, or top-down, processing was reduced by comparing the performance of both ears in participants with a unilateral hearing loss (UHL). We examined the influence of reduced audibility and suprathreshold deficits on speech recognition in quiet and in noise. DESIGN: We measured speech recognition in quiet and stationary speech-shaped noise with consonant-vowel-consonant words and digital triplets in groups of adults with UHL (n = 19), normal hearing (n = 15), and bilateral hearing loss (n = 9). By comparing the scores of the unaffected ear (UHL+) and the affected ear (UHL-) in the UHL group, we were able to isolate the influence of peripheral hearing loss from individual top-down factors such as cognition, linguistic skills, age, and sex. RESULTS: Audibility is a very strong predictor for speech recognition in quiet. Audibility has a less pronounced influence on speech recognition in noise. We found that, for the current sample of listeners, more speech information is required for UHL- than for UHL+ to achieve the same performance. For digit triplets at 80 dBA, the speech recognition threshold in noise (SRT) for UHL- is on average 5.2 dB signal to noise ratio (SNR) poorer than UHL+. Analysis using the speech intelligibility index (SII) indicates that on average 2.1 dB SNR of this decrease can be attributed to suprathreshold deficits and 3.1 dB SNR to audibility. Furthermore, scores for speech recognition in quiet and in noise for UHL+ are comparable to those of normal-hearing listeners. CONCLUSIONS: Our data showed that suprathreshold deficits in addition to audibility play a considerable role in speech recognition in noise even at intensities well above hearing threshold.

Brain Volume Differences Associated With Hearing Impairment in Adults.

Speech comprehension depends on the successful operation of a network of brain regions. Processing of degraded speech is associated with different patterns of brain activity in comparison with that of high-quality speech. In this exploratory study, we studied whether processing degraded auditory input in daily life because of hearing impairment is associated with differences in brain volume. We compared T1-weighted structural magnetic resonance images of 17 hearing-impaired (HI) adults with those of 17 normal-hearing (NH) controls using a voxel-based morphometry analysis. HI adults were individually matched with NH adults based on age and educational level. Gray and white matter brain volumes were compared between the groups by region-of-interest analyses in structures associated with speech processing, and by whole-brain analyses. The results suggest increased gray matter volume in the right angular gyrus and decreased white matter volume in the left fusiform gyrus in HI listeners as compared with NH ones. In the HI group, there was a significant correlation between hearing acuity and cluster volume of the gray matter cluster in the right angular gyrus. This correlation supports the link between partial hearing loss and altered brain volume. The alterations in volume may reflect the operation of compensatory mechanisms that are related to decoding meaning from degraded auditory input.

Comment on "Sensitivity of the Speech Intelligibility Index to the Assumed Dynamic Range," by Jin et al. (2017).

Purpose: This letter to the editor is in response to a research note by Jin, Kates, and Arehart (2017), "Sensitivity of the Speech Intelligibility Index to the Assumed Dynamic Range," published in June 2017 by the Journal of Speech, Language, and Hearing Research. Conclusion: The authors argue that the approach and line of reasoning in the Jin et al. (2017) research note suggest new findings but do not lead to essentially new insights.

Predictors of Entering a Hearing Aid Evaluation Period: A Prospective Study in Older Hearing-Help Seekers.

This study aimed to determine the predictors of entering a hearing aid evaluation period (HAEP) using a prospective design drawing on the health belief model and the transtheoretical model. In total, 377 older persons who presented with hearing problems to an Ear, Nose, and Throat specialist ( n = 110) or a hearing aid dispenser ( n = 267) filled in a baseline questionnaire. After 4 months, it was determined via a telephone interview whether or not participants had decided to enter a HAEP. Multivariable logistic regression analyses were applied to determine which baseline variables predicted HAEP status. A priori, candidate predictors were divided into 'likely' and 'novel' predictors based on the literature. The following variables turned out to be significant predictors: more expected hearing aid benefits, greater social pressure, and greater self-reported hearing disability. In addition, greater hearing loss severity and stigma were predictors in women but not in men. Of note, the predictive effect of self-reported hearing disability was modified by readiness such that with higher readiness, the positive predictive effect became stronger. None of the 'novel' predictors added significant predictive value. The results support the notion that predictors of hearing aid uptake are also predictive of entering a HAEP. This study shows that some of these predictors appear to be gender specific or are dependent on a person's readiness for change. After assuring the external validity of the predictors, an important next step would be to develop prediction rules for use in clinical practice, so that older persons' hearing help-seeking journey can be facilitated.

Effects of attention on the speech reception threshold and pupil response of people with impaired and normal hearing.

For people with hearing difficulties, following a conversation in a noisy environment requires substantial cognitive processing, which is often perceived as effortful. Recent studies with normal hearing (NH) listeners showed that the pupil dilation response, a measure of cognitive processing load, is affected by 'attention related' processes. How these processes affect the pupil dilation response for hearing impaired (HI) listeners remains unknown. Therefore, the current study investigated the effect of auditory attention on various pupil response parameters for 15 NH adults (median age 51 yrs.) and 15 adults with mild to moderate sensorineural hearing loss (median age 52 yrs.). Both groups listened to two different sentences presented simultaneously, one to each ear and partially masked by stationary noise. Participants had to repeat either both sentences or only one, for which they had to divide or focus attention, respectively. When repeating one sentence, the target sentence location (left or right) was either randomized or blocked across trials, which in the latter case allowed for a better spatial focus of attention. The speech-to-noise ratio was adjusted to yield about 50% sentences correct for each task and condition. NH participants had lower ('better') speech reception thresholds (SRT) than HI participants. The pupil measures showed no between-group effects, with the exception of a shorter peak latency for HI participants, which indicated a shorter processing time. Both groups showed higher SRTs and a larger pupil dilation response when two sentences were processed instead of one. Additionally, SRTs were higher and dilation responses were larger for both groups when the target location was randomized instead of fixed. We conclude that although HI participants could cope with less noise than the NH group, their ability to focus attention on a single talker, thereby improving SRTs and lowering cognitive processing load, was preserved. Shorter peak latencies could indicate that HI listeners adapt their listening strategy by not processing some information, which reduces processing time and thereby listening effort.

Impact of stimulus-related factors and hearing impairment on listening effort as indicated by pupil dilation.

Previous research has reported effects of masker type and signal-to-noise ratio (SNR) on listening effort, as indicated by the peak pupil dilation (PPD) relative to baseline during speech recognition. At about 50% correct sentence recognition performance, increasing SNRs generally results in declining PPDs, indicating reduced effort. However, the decline in PPD over SNRs has been observed to be less pronounced for hearing-impaired (HI) compared to normal-hearing (NH) listeners. The presence of a competing talker during speech recognition generally resulted in larger PPDs as compared to the presence of a fluctuating or stationary background noise. The aim of the present study was to examine the interplay between hearing-status, a broad range of SNRs corresponding to sentence recognition performance varying from 0 to 100% correct, and different masker types (stationary noise and single-talker masker) on the PPD during speech perception. Twenty-five HI and 32 age-matched NH participants listened to sentences across a broad range of SNRs, masked with speech from a single talker (-25 dB to +15 dB SNR) or with stationary noise (-12 dB to +16 dB). Correct sentence recognition scores and pupil responses were recorded during stimulus presentation. With a stationary masker, NH listeners show maximum PPD across a relatively narrow range of low SNRs, while HI listeners show relatively large PPD across a wide range of ecological SNRs. With the single-talker masker, maximum PPD was observed in the mid-range of SNRs around 50% correct sentence recognition performance, while smaller PPDs were observed at lower and higher SNRs. Mixed-model ANOVAs revealed significant interactions between hearing-status and SNR on the PPD for both masker types. Our data show a different pattern of PPDs across SNRs between groups, which indicates that listening and the allocation of effort during listening in daily life environments may be different for NH and HI listeners.

The eye as a window to the listening brain: neural correlates of pupil size as a measure of cognitive listening load.

An important aspect of hearing is the degree to which listeners have to deploy effort to understand speech. One promising measure of listening effort is task-evoked pupil dilation. Here, we use functional magnetic resonance imaging (fMRI) to identify the neural correlates of pupil dilation during comprehension of degraded spoken sentences in 17 normal-hearing listeners. Subjects listened to sentences degraded in three different ways: the target female speech was masked by fluctuating noise, by speech from a single male speaker, or the target speech was noise-vocoded. The degree of degradation was individually adapted such that 50% or 84% of the sentences were intelligible. Control conditions included clear speech in quiet, and silent trials. The peak pupil dilation was larger for the 50% compared to the 84% intelligibility condition, and largest for speech masked by the single-talker masker, followed by speech masked by fluctuating noise, and smallest for noise-vocoded speech. Activation in the bilateral superior temporal gyrus (STG) showed the same pattern, with most extensive activation for speech masked by the single-talker masker. Larger peak pupil dilation was associated with more activation in the bilateral STG, bilateral ventral and dorsal anterior cingulate cortex and several frontal brain areas. A subset of the temporal region sensitive to pupil dilation was also sensitive to speech intelligibility and degradation type. These results show that pupil dilation during speech perception in challenging conditions reflects both auditory and cognitive processes that are recruited to cope with degraded speech and the need to segregate target speech from interfering sounds.

The effect of a carrier phrase on hearing aid amplification of single words in quiet.

OBJECTIVE: A common method to assess the functional benefit of hearing aids is by measuring the performance-intensity curve of single words in quiet with and without hearing aids. Currently, virtually all hearing aids use signal processing, which may have a marked effect on gain as a function of time. Thus, hearing-aid behavior may be different for a word presented in isolation compared to the same word preceded by a carrier phrase, which is a closer replication of natural conversation. The present research was conducted to assess this difference. DESIGN: In a hearing-aid test box, speech materials were routed through hearing aids and the output was recorded with a 2cc coupler. STUDY SAMPLE: Seven different hearing aids were programmed according to the manufacturer's fitting rules, using a given hearing loss. RESULTS: Depending on the hearing aid, and the hearing-aid setting, differences in the overall level of the hearing-aid processed words ranged from 1.5 to 3.5 dB. Differences were due to slow attack times in amplitude compression. CONCLUSIONS: Although differences were small for most hearing aids, the use of a carrier phrase should be considered in speech intelligibility tests to ensure that hearing-aid performance closer reflects that in real life.

Modelling the speech reception threshold in non-stationary noise in hearing-impaired listeners as a function of level.

The extended speech intelligibility index (ESII) model (Rhebergen et al, 2006) forms an upgrade to the conventional speech intelligibility index model. For normal-hearing listeners the ESII model is able to predict the speech reception threshold (SRT) in both stationary and non-stationary noise maskers. In this paper, a first attempt is made to evaluate the ESII with SRT data obtained by de Laat and Plomp (1983), and Versfeld and Dreschler (2002) of hearing-impaired listeners in stationary, 10-Hz interrupted, and non-stationary speech-shaped noise measured at different noise levels. The results show that the ESII model is able to describe the SRT in different non-stationary noises for normal-hearing listeners at different noise levels reasonably well. However, the ESII model is less successful in the case of predicting the SRT in non-stationary noise for hearing-impaired subjects. As long as the present audibility models cannot describe the auditory processing in a listener with cochlear hearing loss accurately, it is difficult to distinguish between raised SRTs due to supra-threshold deficits or factors such as cognition, age, and language skills.

The dynamic range of speech, compression, and its effect on the speech reception threshold in stationary and interrupted noise.

Changes in the speech reception threshold (SRT) after amplitude compression of speech or speech in noise may be due to changes in the dynamic range of the speech signal. However, current models set up to predict the speech intelligibility consider the dynamic range of speech to be fixed regardless of the type of compression. The present paper describes two experiments with normal-hearing subjects to examine the effect of the dynamic range on the SRT in stationary and interrupted noise after wide dynamic range compression. The dynamic range has been varied by compression or expansion of only the speech signal, leaving the masking noise unaltered, or by compression or expansion of the mixed speech-in-noise signal. The results show that compression affects the SRT, both in a positive or a negative direction, not only due to dynamic range but also due to distortion of the speech signal.

Prediction of the intelligibility for speech in real-life background noises for subjects with normal hearing.

OBJECTIVES: The speech reception threshold (SRT) traditionally is measured in stationary noise that has the long-term average speech spectrum of the target speech. However, in real life the instantaneous spectrum of the background noise is likely to be different from the stationary long-term average speech spectrum noise. To gain more insight into the effect of real-life background noises on speech intelligibility, the SRT of listeners with normal hearing was measured in a set of noises that varied in both the spectral and the temporal domain. This article investigates the ability of the extended speech intelligibility index (ESII), proposed by Rhebergen et al. to account for SRTs in these real-life background noises. DESIGN: SRTs in noise were measured in 12 subjects with normal hearing. Interfering noises consisted of a variety of real-life noises, selected from a database, and chosen on the basis of their spectrotemporal differences. Measured SRTs were converted to ESII values and compared. Ideally, at threshold, ESII values should be the same, because the ESII represents the amount of speech information available to the listener. RESULTS: SRTs ranged from -6 dB SNR (in stationary noise) to -21 dB SNR (in machine gun noise). Conversion to ESII values resulted in an average value of 0.34, with a standard deviation of 0.06. SRT predictions with the ESII model were better than those obtained with the conventional SII (ANSI 53.5-1997) model. In case of interfering speech, the ESII model predictions were poorer, because additional, nonenergetic (informational) masking is thought to occur. CONCLUSIONS: For the present set of masking noises, being representative for a variety of real-life noises, the ESII model of Rhebergen et al. is able to predict the SRTs of subjects with normal hearing with reasonable accuracy. It may be concluded that the ESII model can provide valuable predictions for the speech intelligibility in some everyday situations.