The one-up one-down adaptive (staircase) procedure in speech-in-noise testing: Standard error of measurement and fluctuations in the track.

The one-up one-down adaptive (staircase or up-down) procedure is often used to estimate the speech recognition threshold (SRT) in speech-in-noise testing. This article provides a brief historical overview of the one-up one-down procedure in psychophysics, discussing the groundbreaking early work that is still relevant to clinical audiology and scientific research. Next, this article focuses on two aspects of the one-up one-down adaptive procedure: first, the standard error of measurement (SEM) and, second, the fluctuations in the track [i.e., the standard deviation of the signal-to-noise ratios of the stimuli within the track (SDtrack)]. Simulations of ideal and non-ideal listeners and experimental data are used to determine and evaluate different relationships between the parameters slope of the speech recognition function, SRT, SEM, and SDtrack. Hearing loss and non-ideal behavior (inattentiveness, fatigue, and giving up when the task becomes too difficult) slightly increase the average value of SDtrack. SDtrack, however, poorly discriminates between reliable and unreliable SRT estimates.

The Influence of Linguistic Proficiency on Masked Text Recognition Performance in Adults With and Without Congenital Hearing Impairment.

OBJECTIVE: The authors first examined the influence of moderate to severe congenital hearing impairment (CHI) on the correctness of samples of elicited spoken language. Then, the authors used this measure as an indicator of linguistic proficiency and examined its effect on performance in language reception, independent of bottom-up auditory processing. DESIGN: In groups of adults with normal hearing (NH, n = 22), acquired hearing impairment (AHI, n = 22), and moderate to severe CHI (n = 21), the authors assessed linguistic proficiency by analyzing the morphosyntactic correctness of their spoken language production. Language reception skills were examined with a task for masked sentence recognition in the visual domain (text), at a readability level of 50%, using grammatically correct sentences and sentences with distorted morphosyntactic cues. The actual performance on the tasks was compared between groups. RESULTS: Adults with CHI made more morphosyntactic errors in spoken language production than adults with NH, while no differences were observed between the AHI and NH group. This outcome pattern sustained when comparisons were restricted to subgroups of AHI and CHI adults, matched for current auditory speech reception abilities. The data yielded no differences between groups in performance in masked text recognition of grammatically correct sentences in a test condition in which subjects could fully take advantage of their linguistic knowledge. Also, no difference between groups was found in the sensitivity to morphosyntactic distortions when processing short masked sentences, presented visually. CONCLUSIONS: These data showed that problems with the correct use of specific morphosyntactic knowledge in spoken language production are a long-term effect of moderate to severe CHI, independent of current auditory processing abilities. However, moderate to severe CHI generally does not impede performance in masked language reception in the visual modality, as measured in this study with short, degraded sentences. Aspects of linguistic proficiency that are affected by CHI thus do not seem to play a role in masked sentence recognition in the visual modality.

Change in Psychosocial Health Status Over 5 Years in Relation to Adults' Hearing Ability in Noise.

OBJECTIVES: The aim of this study was to establish the longitudinal relationship between hearing ability in noise and psychosocial health outcomes (i.e., loneliness, anxiety, depression, distress, and somatization) in adults aged 18 to 70 years. An additional objective was to determine whether a change in hearing ability in noise over a period of 5 years was associated with a change in psychosocial functioning. Subgroup effects for a range of factors were investigated. DESIGN: Longitudinal data of the web-based Netherlands Longitudinal Study on Hearing (NL-SH) (N = 508) were analyzed. The ability to recognize speech in noise (i.e., the speech-reception-threshold [SRTn]) was measured with an online digit triplet test at baseline and at 5-year follow-up. Psychosocial health status was assessed by online questionnaires. Multiple linear regression analyses and longitudinal statistical analyses (i.e., generalized estimating equations) were performed. RESULTS: Poorer SRTn was associated longitudinally with more feelings of emotional and social loneliness. For participants with a high educational level, the longitudinal association between SRTn and social loneliness was significant. Changes in hearing ability and loneliness appeared significantly associated only for specific subgroups: those with stable pattern of hearing aid nonuse (increased emotional and social loneliness), who entered matrimony (increased social loneliness), and low educational level (less emotional loneliness). No significant longitudinal associations were found between hearing ability and anxiety, depression, distress, or somatization. CONCLUSIONS: Hearing ability in noise was longitudinally associated with loneliness. Decline in hearing ability in noise was related to increase in loneliness for specific subgroups of participants. One of these subgroups included participants whose hearing deteriorated over 5 years, but who continued to report nonuse of hearing aids. This is an important and alarming finding that needs further investigation.

The influence of lexical-access ability and vocabulary knowledge on measures of speech recognition in noise.

OBJECTIVE: The main objective was to investigate the effect of linguistic abilities (lexical-access ability and vocabulary size) on different measures of speech-in-noise recognition in normal-hearing listeners with various levels of language proficiency. DESIGN: Speech reception thresholds (SRTs) were measured for sentences in steady-state (SRTstat) and fluctuating noise (SRTfluc), and for digit-triplets in steady-state noise (DIN). Lexical-access ability was measured with a lexical-decision test and a word-naming test. Vocabulary size was also measured. For the SRT, keyword scoring and sentence scoring were compared. STUDY SAMPLE: To introduce variation in linguistic abilities, three groups of 24 young normal-hearing listeners were included: higher-educated native, lower-educated native, and higher-educated non-native listeners. RESULTS: Lexical-access ability was most accurately measured with combined results of lexical decision and word naming. Lexical-access ability explained 60% of the variance in SRT. The effect of linguistic abilities on SRTs was up to 5.6 dB for SRTstat and 8 dB for SRTfluc. Using keyword scoring reduced this effect by approximately 1.5 dB. For DIN the effect of linguistic ability was less than 1 dB. CONCLUSIONS: Lexical-access ability is an important predictor of SRTs in normal-hearing listeners. These results are important to consider in the interpretation of speech-in-noise scores of hearing-impaired listeners.

Medication Use in Adults with and without Hearing Impairment.

The objective of this study was to determine whether hearing ability in adults is associated with medication use in general, the use of specific types of medication, or polypharmacy. In this exploratory study, data of the National Longitudinal Study on Hearing (NL-SH; n = 2,160) were used. In total, 62% of the participants reported using any medication in the past 28 days. Hearing ability in noise, as determined with an online digit-triplet speech-in-noise test, was significantly associated with (1) medication acting on the alimentary tract and metabolism (including diabetes and acid-related disorders), (2) use of calcium blockers, and (3) medication used for sensory organs.

Speech-in-speech listening on the LiSN-S test by older adults with good audiograms depends on cognition and hearing acuity at high frequencies.

OBJECTIVES: The main objective was to investigate age-related differences on the listening in spatialized noise-sentences (LiSN-S) test in adults with normal audiometric thresholds in most of the speech range. A second objective was to examine the contributions of auditory, cognitive, and linguistic abilities to LiSN-S outcomes. DESIGN: The LiSN-S test was administered to participants in an older group (M(Age) = 72.0, SD = 4.3 years) and a younger group (M(Age) = 21.7, SD = 2.6 years) with N = 26 per group. All the participants had clinically normal audiometric thresholds at frequencies up to and including 3000 Hz. The LiSN-S test yields a speech reception threshold (SRT) in each of the four speech-in-speech listening conditions that differ in the availability of voice difference cues and/or spatial separation cues. Based on these four SRTs, the scores were calculated for the talker advantage, the spatial advantage, and the total advantage as a result of both the types of cues. Additionally, the participants completed four auditory temporal-processing tests, a cognitive screening test, a vocabulary test, and tests of linguistic closure for high- and low-context sentences. The contributions of these predictor variables and measures of pure-tone hearing acuity to LiSN-S outcomes were analyzed for both the groups using regression analyses. RESULTS: Younger listeners outperformed the older listeners on all four LiSN-S SRTs and all the three LiSN-S advantage measures. Age-related differences were larger for conditions involving the use of spatial cues. For the younger group, all LiSN-S SRTs were predicted by the measure of linguistic closure in low-context sentences; in addition, the SRT for the condition with voice difference cues but without spatial separation cues was predicted by vocabulary, and the SRT for the condition with both voice difference cues and spatial separation cues was predicted by temporal resolution at low frequencies. Vocabulary also contributed to the talker advantage in the younger group, whereas the spatial advantage was predicted by high-frequency pure-tone hearing acuity in the range 6,000 to 10,000 Hz (pure-tone average [PTA](HIGH)). For the older group, the LiSN-S SRT in the condition with neither voice difference cues nor spatial separation cues was predicted by age; their other three LiSN-S SRTs and all advantage measures were predicted by PTA(HIGH). In addition, for the older group, cognition predicted LiSN-S SRT outcomes in three of the four conditions. Measures of auditory temporal processing, linguistic abilities, or hearing acuity up to and including 4000 Hz did not predict LiSN-S outcomes in this group. CONCLUSIONS: LiSN-S outcomes were poorer for adults aged 65 years or older, even those with good audiograms, compared with younger adults and also compared with people up to the age of 60 years from a previous study. In the present study, regardless of the types of cues, auditory and cognitive interactions were reflected by the combined influences on LiSN-S outcomes of high-frequency hearing acuity and measures of linguistic and cognitive processing. The data also suggest a hierarchy in the deployment of processing resources, which would account for the observed shift from linguistic abilities in the younger group to general cognitive abilities in the older group.

Deterioration of Speech Recognition Ability Over a Period of 5 Years in Adults Ages 18 to 70 Years: Results of the Dutch Online Speech-in-Noise Test.

OBJECTIVES: The first aim of the present study was to determine the change in speech recognition in noise over a period of 5 years in participants ages 18 to 70 years at baseline. The second aim was to investigate whether age, gender, educational level, the level of initial speech recognition in noise, and reported chronic conditions were associated with a change in speech recognition in noise. DESIGN: The baseline and 5-year follow-up data of 427 participants with and without hearing impairment participating in the National Longitudinal Study on Hearing (NL-SH) were analyzed. The ability to recognize speech in noise was measured twice with the online National Hearing Test, a digit-triplet speech-in-noise test. Speech-reception-threshold in noise (SRTn) scores were calculated, corresponding to 50% speech intelligibility. Unaided SRTn scores obtained with the same transducer (headphones or loudspeakers) at both test moments were included. Changes in SRTn were calculated as a raw shift (T1 - T0) and an adjusted shift for regression towards the mean. Paired t tests and multivariable linear regression analyses were applied. RESULTS: The mean increase (i.e., deterioration) in SRTn was 0.38-dB signal-to-noise ratio (SNR) over 5 years (p < 0.001). Results of the multivariable regression analyses showed that the age group of 50 to 59 years had a significantly larger deterioration in SRTn compared with the age group of 18 to 39 years (raw shift: beta: 0.64-dB SNR; 95% confidence interval: 0.07-1.22; p = 0.028, adjusted for initial speech recognition level - adjusted shift: beta: 0.82-dB SNR; 95% confidence interval: 0.27-1.34; p = 0.004). Gender, educational level, and the number of chronic conditions were not associated with a change in SRTn over time. No significant differences in increase of SRTn were found between the initial levels of speech recognition (i.e., good, insufficient, or poor) when taking into account the phenomenon regression towards the mean. CONCLUSIONS: The study results indicate that hearing deterioration of speech recognition in noise over 5 years can also be detected in adults ages 18 to 70 years. This rather small numeric change might represent a relevant impact on an individual's ability to understand speech in everyday life.

Assessing speech recognition abilities with digits in noise in cochlear implant and hearing aid users.

OBJECTIVE: The primary objective of the study was to investigate the feasibility, reliability, and validity of the Dutch digits in noise (DIN) test for measuring speech recognition in hearing aid and cochlear implant users and compare results to the standard sentences-in-noise (SIN) test. DESIGN: The relation between speech reception thresholds for DIN test and SIN test was analysed to determine the validity of the DIN test. As linguistic skills were expected to make different contributions in these tests, their influence was analysed. STUDY SAMPLE: Participants were 12 normal-hearing listeners, 24 hearing aid users, and 24 cochlear implant users. RESULTS: The DIN test was feasible for more participants than the SIN test. Intraclass correlation coefficients showed high reliability. The standard error of measurement was smaller for the DIN test than for the SIN test. DIN test and SIN test were highly correlated (r = 0.95 and r = 0.56 for NH+ HA and CI users respectively). In the regression analysis no significant contribution of basic linguistic skills or personal factors was found. CONCLUSION: In the assessment of speech recognition in noise of aided hearing-impaired listeners with hearing aids or cochlear implants, the DIN test is a feasible, reliable and valid test.

The influence of informational masking on speech perception and pupil response in adults with hearing impairment.

A recent pupillometry study on adults with normal hearing indicates that the pupil response during speech perception (cognitive processing load) is strongly affected by the type of speech masker. The current study extends these results by recording the pupil response in 32 participants with hearing impairment (mean age 59 yr) while they were listening to sentences masked by fluctuating noise or a single-talker. Efforts were made to improve audibility of all sounds by means of spectral shaping. Additionally, participants performed tests measuring verbal working memory capacity, inhibition of interfering information in working memory, and linguistic closure. The results showed worse speech reception thresholds for speech masked by single-talker speech compared to fluctuating noise. In line with previous results for participants with normal hearing, the pupil response was larger when listening to speech masked by a single-talker compared to fluctuating noise. Regression analysis revealed that larger working memory capacity and better inhibition of interfering information related to better speech reception thresholds, but these variables did not account for inter-individual differences in the pupil response. In conclusion, people with hearing impairment show more cognitive load during speech processing when there is interfering speech compared to fluctuating noise.

Comorbidity in adults with hearing difficulties: which chronic medical conditions are related to hearing impairment?

OBJECTIVES: To investigate the occurrence of 27 chronic medical conditions in a cohort of adults with and without hearing impairment, and to examine the association between these conditions and hearing ability. DESIGN: The National Longitudinal Study on Hearing (NL-SH study) is a large prospective study among adults aged 18 to 70 years, conducted via the internet in the Netherlands. Hearing ability was measured with a digits-in-noise test and comorbidity was assessed through self-report. STUDY SAMPLE: Cross-sectional data of 890 hearing-impaired and 975 normally-hearing adults were analyzed. Both descriptive statistics and multinomial logistic regression analyses were conducted. RESULTS: Of the NL-SH participants with insufficient or poor hearing ability, 78.5% reported to suffer from at least one additional chronic condition. This proportion was larger than in the normally-hearing group (68.6% with one or more chronic conditions and 37.7% with two or more). After adjustment for age and gender, 'dizziness causing falling', 'diabetes' and 'arthritis types other than osteoarthritis and rheumatic arthritis' were significantly associated with poor hearing ability. CONCLUSIONS: Our results show that some previously reported associations do not only occur in older age groups, but also in younger cohorts. Comorbidity is relevant in the rehabilitation (multi-disciplinary care) and the clinical encounter.

Decline in older persons' ability to recognize speech in noise: the influence of demographic, health-related, environmental, and cognitive factors.

OBJECTIVES: The first aim was to investigate whether the rate of decline in older persons' ability to recognize speech in noise over time differs across age and gender. The second aim was to determine extent demographic, health-related, environmental, and cognitive factors influence the change in speech-in-noise recognition over time. DESIGN: Data covering 3 to 7 years of follow-up (mean: 4.9 years) of a large sample of the Longitudinal Aging Study Amsterdam were used (n = 1298; 3025 observations; baseline ages: 57 to 93 years). Hearing ability was measured by a digit triplet speech-in-noise test (SNT) yielding a speech reception threshold in noise (SRTn). Multilevel analyses were used to model the change in SRTn over time. First, interaction terms were used to test differences in rate of decline across subgroups. Second, for each of the following factors the authors determined the influence on the change in SRTn: age, gender, educational level, cardiovascular conditions, information processing speed, fluid intelligence, global cognitive functioning, smoking, and alcohol use. This was done by calculating the percentage change in Btime after adding the particular factor to the model. RESULTS: On average, respondents' SRTn increased (i.e., deteriorated) significantly over time by 0.18 dB signal-to-noise ratio per annum. Rates were accelerated for older ages (Btime = 0.13, 0.14, 0.25, 0.27 for persons who were 57 to 65, 65 to 75, 75 to 85, and 85 to 93 years of age, respectively). Only information processing speed relevantly influenced the change in SRTn over time (17% decrease in Btime). CONCLUSIONS: Decline in older persons' speech-in-noise recognition over time accelerated for older ages. Decline in information processing speed explained a moderate proportion of the SRTn decline. This indicates the relevance of declining cognitive abilities in the ability of older persons to recognize speech in noisy environments.

Dual sensory loss: development of a dual sensory loss protocol and design of a randomized controlled trial.

BACKGROUND: Dual sensory loss (DSL) has a negative impact on health and wellbeing and its prevalence is expected to increase due to demographic aging. However, specialized care or rehabilitation programs for DSL are scarce. Until now, low vision rehabilitation does not sufficiently target concurrent impairments in vision and hearing. This study aims to 1) develop a DSL protocol (for occupational therapists working in low vision rehabilitation) which focuses on optimal use of the senses and teaches DSL patients and their communication partners to use effective communication strategies, and 2) describe the multicenter parallel randomized controlled trial (RCT) designed to test the effectiveness and cost-effectiveness of the DSL protocol. METHODS/DESIGN: To develop a DSL protocol, literature was reviewed and content was discussed with professionals in eye/ear care (interviews/focus groups) and DSL patients (interviews). A pilot study was conducted to test and confirm the DSL protocol. In addition, a two-armed international multi-center RCT will evaluate the effectiveness and cost-effectiveness of the DSL protocol compared to waiting list controls, in 124 patients in low vision rehabilitation centers in the Netherlands and Belgium. DISCUSSION: This study provides a treatment protocol for rehabilitation of DSL within low vision rehabilitation, which aims to be a valuable addition to the general low vision rehabilitation care. TRIAL REGISTRATION: Netherlands Trial Register (NTR) identifier: NTR2843.

The interpretation of speech reception threshold data in normal-hearing and hearing-impaired listeners: II. Fluctuating noise.

Following previous work [Smits and Festen. (2011). J. Acoust. Soc. Am. 130, 2987-2998] involving the interpretation of speech reception threshold (SRT) data in steady-state noise, the present study considers fluctuating noise. Whereas the SIIsteady function [i.e., the speech intelligibility index (SII) against SNR in steady-state noise] can be approximated by a simple linear function going from 0 to 1 between SNR = -15 dB to +15 dB, the SIIfluc function is a function over a broader range than 30 dB and its maximum lies at a SNR higher than +15 dB. The difference in shape between the SIIsteady and SIIfluc functions has several implications. It predicts a reduction in fluctuating masker benefit (FMB), or even a negative FMB, for higher SNRs for normal-hearing listeners. Experimental data confirm this prediction. Much of the reduction in FMB for hearing-impaired listeners may be attributed to the higher SRTs in steady-state noise for these listeners.

The digits-in-noise test: assessing auditory speech recognition abilities in noise.

A speech-in-noise test which uses digit triplets in steady-state speech noise was developed. The test measures primarily the auditory, or bottom-up, speech recognition abilities in noise. Digit triplets were formed by concatenating single digits spoken by a male speaker. Level corrections were made to individual digits to create a set of homogeneous digit triplets with steep speech recognition functions. The test measures the speech reception threshold (SRT) in long-term average speech-spectrum noise via a 1-up, 1-down adaptive procedure with a measurement error of 0.7 dB. One training list is needed for naive listeners. No further learning effects were observed in 24 subsequent SRT measurements. The test was validated by comparing results on the test with results on the standard sentences-in-noise test. To avoid the confounding of hearing loss, age, and linguistic skills, these measurements were performed in normal-hearing subjects with simulated hearing loss. The signals were spectrally smeared and/or low-pass filtered at varying cutoff frequencies. After correction for measurement error the correlation coefficient between SRTs measured with both tests equaled 0.96. Finally, the feasibility of the test was approved in a study where reference SRT values were gathered in a representative set of 1386 listeners over 60 years of age.

Hearing ability in working life and its relationship with sick leave and self-reported work productivity.

OBJECTIVES: Reduced hearing ability has been shown to influence various aspects of daily life, such as communication, psychosocial functioning, and working life. The aim of this study is to examine the association between hearing ability in noise and both sick leave and self-reported work productivity. In addition, the relationship between hearing ability and perceived health-caused limitations at work is examined. METHODS: Data were collected at the baseline measurement of the Dutch "National Longitudinal Study on Hearing" and at each month during a subsequent period of 3 mo. Hearing ability was determined by means of the National Hearing Test, a speech-in-noise test over the Internet using digit triplets. The sample comprised 748 workers (385 with normal hearing ability and 363 with insufficient or poor hearing ability). RESULTS: Linear regression analyses revealed a significant adverse association between reduced hearing ability and self-reported absolute and differential productivity; for every dB signal-to-noise ratio (dB SNR) poorer hearing ability, self-rated absolute productivity for people experiencing little social support decreased by 0.054 points on a scale from 0 to 10 (b = -0.054; 95% confidence interval [CI] = -0.088 to -0.02). For people with less than three other chronic conditions, self-rated differential productivity also decreased significantly with decreasing hearing ability (no chronic conditions: b = -0.048 points/dB SNR on a scale from -10 to + 10, 95% CI = -0.094 to -0.001; one or two other chronic conditions: b = -0.035 points/dB SNR, 95% CI = -0.067 to -0.002). With adjustment for confounders, poorer hearing ability in noise furthermore significantly increased the odds for experiencing limitations (in the type or amount of work one could do) sometimes (odds ratio = 1.14; 95% CI = 1.07-1.21) and often to very often (odds ratio = 1.24; 95% CI = 1.05-1.45) in comparison with experiencing limitation seldom to never. A higher level of need for recovery among people with poorer hearing ability appeared to be one of the factors mediating the higher odds for sick leave of more than 5 days. CONCLUSION: Reduced hearing ability in noise was significantly associated with a lower self-reported absolute and differential productivity in specific cases. Also, poorer hearing increased the odds for experiencing health-caused limitations in the type or amount of work one can do. The significant relationship between hearing ability and sick leave, which was found when not adjusting for confounders, could partly be explained by a higher need for recovery among people with reduced hearing ability in noise.

Pupil dilation uncovers extra listening effort in the presence of a single-talker masker.

OBJECTIVES: Recent research has demonstrated that pupil dilation, a measure of mental effort (cognitive processing load), is sensitive to differences in speech intelligibility. The present study extends this outcome by examining the effects of masker type and age on the speech reception threshold (SRT) and mental effort. DESIGN: In young and middle-aged adults, pupil dilation was measured while they performed an SRT task, in which spoken sentences were presented in stationary noise, fluctuating noise, or together with a single-talker masker. The masker levels were adjusted to achieve 50% or 84% sentence intelligibility. RESULTS: The results show better SRTs for fluctuating noise and a single-talker masker compared with stationary noise, which replicates results of previous studies. The peak pupil dilation, reflecting mental effort, was larger in the single-interfering speaker condition compared with the other masker conditions. Remarkably, in contrast to the thresholds, no differences in peak dilation were observed between fluctuating noise and stationary noise. This effect was independent of the intelligibility level and age. CONCLUSIONS: To maintain similar intelligibility levels, participants needed more mental effort for speech perception in the presence of a single-talker masker and then with the two other types of maskers. This suggests an additive interfering effect of speech information from the single-talker masker. The dissociation between these performance and mental effort measures underlines the importance of including measurements of pupil dilation as an independent index of mental effort during speech processing in different types of noisy environments and at different intelligibility levels.

Cost-effectiveness of a vocational enablement protocol for employees with hearing impairment; design of a randomized controlled trial.

BACKGROUND: Hearing impairment at the workplace, and the resulting psychosocial problems are a major health problem with substantial costs for employees, companies, and society. Therefore, it is important to develop interventions to support hearing impaired employees. The objective of this article is to describe the design of a randomized controlled trial evaluating the (cost-) effectiveness of a Vocational Enablement Protocol (VEP) compared with usual care. METHODS/DESIGN: Participants will be selected with the 'Hearing and Distress Screener'. The study population will consist of 160 hearing impaired employees. The VEP intervention group will be compared with usual care. The VEP integrated care programme consists of a multidisciplinary assessment of auditory function, work demands, and personal characteristics. The goal of the intervention is to facilitate participation in work. The primary outcome measure of the study is 'need for recovery after work'. Secondary outcome measures are coping with hearing impairment, distress, self-efficacy, psychosocial workload, job control, general health status, sick leave, work productivity, and health care use. Outcome measures will be assessed by questionnaires at baseline, and 3, 6, 9, and 12 months after baseline. The economic evaluation will be performed from both a societal and a company perspective. A process evaluation will also be performed. DISCUSSION: Interventions addressing occupational difficulties of hearing impaired employees are rare but highly needed. If the VEP integrated care programme proves to be (cost-) effective, the intervention can have an impact on the well-being of hearing impaired employees, and thereby, on the costs for the company as well for the society. TRIAL REGISTRATION: Netherlands Trial Register (NTR): NTR2782.

Effects of reverberation and masker fluctuations on binaural unmasking of speech.

In daily life, listeners use two ears to understand speech in situations which typically include reverberation and non-stationary noise. In headphone experiments, the binaural benefit for speech in noise is often expressed as the difference in speech reception threshold between diotic (N(0)S(0)) and dichotic (N(0)S(π)) conditions. This binaural advantage (BA), arising from the use of inter-aural phase differences, is about 5-6 dB in stationary noise, but may be lower in everyday conditions. In the current study, BA was measured in various combinations of noise and artificially created diotic reverberation, for normal-hearing and hearing-impaired listeners. Speech-intelligibility models were applied to quantify the combined effects. Results showed that in stationary noise, diotic reverberation did not affect BA. BA was reduced in conditions where the masker fluctuated. With additional reverberation, however, it was restored. Results for both normal-hearing and hearing-impaired listeners were accounted for by assuming that binaural unmasking is only effectively realized at low instantaneous speech-to-noise ratios (SNRs). The observed BA was related to the distribution of SNRs resulting from fluctuations, reverberation, and peripheral processing. It appears that masker fluctuations and reverberation, both relevant for everyday communication, interact in their effects on binaural unmasking and need to be considered together.

Cognitive load during speech perception in noise: the influence of age, hearing loss, and cognition on the pupil response.

OBJECTIVES: The aim of the present study was to evaluate the influence of age, hearing loss, and cognitive ability on the cognitive processing load during listening to speech presented in noise. Cognitive load was assessed by means of pupillometry (i.e., examination of pupil dilation), supplemented with subjective ratings. DESIGN: Two groups of subjects participated: 38 middle-aged participants (mean age = 55 yrs) with normal hearing and 36 middle-aged participants (mean age = 61 yrs) with hearing loss. Using three Speech Reception Threshold (SRT) in stationary noise tests, we estimated the speech-to-noise ratios (SNRs) required for the correct repetition of 50%, 71%, or 84% of the sentences (SRT50%, SRT71%, and SRT84%, respectively). We examined the pupil response during listening: the peak amplitude, the peak latency, the mean dilation, and the pupil response duration. For each condition, participants rated the experienced listening effort and estimated their performance level. Participants also performed the Text Reception Threshold (TRT) test, a test of processing speed, and a word vocabulary test. Data were compared with previously published data from young participants with normal hearing. RESULTS: Hearing loss was related to relatively poor SRTs, and higher speech intelligibility was associated with lower effort and higher performance ratings. For listeners with normal hearing, increasing age was associated with poorer TRTs and slower processing speed but with larger word vocabulary. A multivariate repeated-measures analysis of variance indicated main effects of group and SNR and an interaction effect between these factors on the pupil response. The peak latency was relatively short and the mean dilation was relatively small at low intelligibility levels for the middle-aged groups, whereas the reverse was observed for high intelligibility levels. The decrease in the pupil response as a function of increasing SNR was relatively small for the listeners with hearing loss. Spearman correlation coefficients indicated that the cognitive load was larger in listeners with better TRT performances as reflected by a longer peak latency (normal-hearing participants, SRT50% condition) and a larger peak amplitude and longer response duration (hearing-impaired participants, SRT50% and SRT84% conditions). Also, a larger word vocabulary was related to longer response duration in the SRT84% condition for the participants with normal hearing. CONCLUSIONS: The pupil response systematically increased with decreasing speech intelligibility. Ageing and hearing loss were related to less release from effort when increasing the intelligibility of speech in noise. In difficult listening conditions, these factors may induce cognitive overload relatively early or they may be associated with relatively shallow speech processing. More research is needed to elucidate the underlying mechanisms explaining these results. Better TRTs and larger word vocabulary were related to higher mental processing load across speech intelligibility levels. This indicates that utilizing linguistic ability to improve speech perception is associated with increased listening load.

The influence of semantically related and unrelated text cues on the intelligibility of sentences in noise.

OBJECTIVES: In two experiments with different subject groups, we explored the relationship between semantic context and intelligibility by examining the influence of visually presented, semantically related, and unrelated three-word text cues on perception of spoken sentences in stationary noise across a range of speech-to-noise ratios (SNRs). In addition, in Experiment (Exp) 2, we explored the relationship between individual differences in cognitive factors and the effect of the cues on speech intelligibility. DESIGN: In Exp 1, cues had been generated by participants themselves in a previous test session (own) or by someone else (alien). These cues were either appropriate for that sentence (match) or for a different sentence (mismatch). A condition with nonword cues, generated by the experimenter, served as a control. Experimental sentences were presented at three SNRs (dB SNR) corresponding to the entirely correct repetition of 29%, 50%, or 71% of sentences (speech reception thresholds; SRTs). In Exp 2, semantically matching or mismatching cues and nonword cues were presented before sentences at SNRs corresponding to SRTs of 16% and 29%. The participants in Exp 2 also performed tests of verbal working memory capacity and the ability to read partially masked text. RESULTS: In Exp 1, matching cues improved perception relative to the nonword and mismatching cues, with largest benefits at the SNR corresponding to 29% performance in the SRT task. Mismatching cues did not impair speech perception relative to the nonword cue condition, and no difference in the effect of own and alien matching cues was observed. In Exp 2, matching cues improved speech perception as measured using both the percentage of correctly reported words and the percentage of entirely correctly reported sentences. Mismatching cues reduced the percentage of repeated words (but not the sentence-based scores) compared with the nonword cue condition. Working memory capacity and ability to read partly masked sentences were positively associated with the number of sentences repeated entirely correctly in the mismatch condition at the 29% SNR. CONCLUSIONS: In difficult listening conditions, both relevant and irrelevant semantic context can influence speech perception in noise. High working memory capacity and good linguistic skills are associated with a greater ability to inhibit irrelevant context when uncued sentence intelligibility is around 29% correct.