Effect of a single lateral diffuse reflection on spatial percepts and speech intelligibility.

This study examines the influence of an early lateral reflection on spatial perceptual attributes and speech reception. To this aim, a diffuse reflection is compared with a specular one. Although diffusive surfaces have widespread applications in room acoustics design, the knowledge of the perceptual and behavioral outcomes of these surfaces has yet to be fully developed. Two experiments were conducted to investigate how the reflection type, its temporal delay, and its azimuth affect spatial percepts (source distance, width, and focus) and speech intelligibility (SI) in diffuse stationary noise. The experimental setup included ecological elements: field measurements, a speaker-like source directivity, and real flat and diffusive surfaces. The results indicate that the presence of a single diffuse reflection reduces the perceived distance of a frontal speech source and makes it clearer. SI is higher with a diffuse reflection than with a specular one. Perceptual and behavioral outcomes both depend on the angle of reflection given the frequency- and angular-dependent properties of the diffusing surface and the directivity of the speech source. The results are interpreted with reference to loudness and binaural cues and to the precedence effect. Implications of the findings for acoustic design are also discussed.

Relative contributions of auditory and cognitive functions on speech recognition in quiet and in noise among older adults / Contribuições relativas das funções auditivas e cognitivas no reconhecimento da fala no silêncio e no ruído entre idosos

Abstract Introduction: Hearing acuity, central auditory processing and cognition contribute to the speech recognition difficulty experienced by older adults. Therefore, quantifying the contribution of these factors on speech recognition problem is important in order to formulate a holistic and effective rehabilitation. Objective: To examine the relative contributions of auditory functioning and cognition status to speech recognition in quiet and in noise. Methods: We measured speech recognition in quiet and in composite noise using the Malay Hearing in noise test on 72 native Malay speakers (60-82 years) older adults with normal to mild hearing loss. Auditory function included pure tone audiogram, gaps-in-noise, and dichotic digit tests. Cognitive function was assessed using the Malay Montreal cognitive assessment. Results: Linear regression analyses using backward elimination technique revealed that had the better ear four frequency average (0.5-4 kHz) (4FA), high frequency average and Malay Montreal cognitive assessment attributed to speech perception in quiet (total r2 = 0.499). On the other hand, high frequency average, Malay Montreal cognitive assessment and dichotic digit tests contributed significantly to speech recognition in noise (total r2 = 0.307). Whereas the better ear high frequency average primarily measured the speech recognition in quiet, the speech recognition in noise was mainly measured by cognitive function. Conclusions: These findings highlight the fact that besides hearing sensitivity, cognition plays an important role in speech recognition ability among older adults, especially in noisy environments. Therefore, in addition to hearing aids, rehabilitation, which trains cognition, may have a role in improving speech recognition in noise ability of older adults.

Resumo Introdução: A alteração da acuidade auditiva, do processamento auditivo central e da cognição são fatores que contribuem para a dificuldade de reconhecimento da fala em idosos. Portanto, quantificar a contribuição desses fatores no problema de reconhecimento da fala é importante para a formulação de uma reabilitação holística e efetiva. Objetivo: Examinar as contribuições relativas do funcionamento auditivo e do estado cognitivo para o reconhecimento da fala no silêncio e no ruído. Método: Nós medimos o reconhecimento de fala no silêncio e no ruído composto com o teste Malay hearing in noise test em 72 idosos malaios nativos falantes (60-82 anos) com audição normal a perda auditiva de grau leve. A avaliação da função auditiva incluiu audiograma de tons puros, teste gaps-in-noise e testes dicótico de dígitos. A função cognitiva foi avaliada pelo teste Malay Montreal cognitive assessment. Resultados: Análises de regressão linear com técnicas de eliminação backward na orelha melhor revelaram média de quatro frequências (0,5-4 kHz) (4AF), média de alta frequência e teste Malay Montreal cognitive assessment na orelha melhor, mensurada pela percepção da fala no silêncio (r2 total = 0,499). Por outro lado, a média de alta frequência, Malay Montreal cognitive assessment e o teste dicótico de dígitos contribuíram significativamente para o reconhecimento da fala no ruído (r2 total = 0,307). Enquanto a média de alta frequência da melhor orelha mediu principalmente o reconhecimento da fala no silêncio, o reconhecimento da fala no ruído foi mensurado principalmente pela função cognitiva. Conclusões: Esses achados destacam o fato de que, além da sensibilidade auditiva, a cognição desempenha um papel importante na capacidade de reconhecimento da fala em idosos, principalmente em ambientes ruidosos. Portanto, além de aparelhos auditivos, a reabilitação, que treina a cognição, pode ter um papel na melhoria da capacidade do reconhecimento da fala no ruído entre os idosos.

Relative contributions of auditory and cognitive functions on speech recognition in quiet and in noise among older adults.

INTRODUCTION: Hearing acuity, central auditory processing and cognition contribute to the speech recognition difficulty experienced by older adults. Therefore, quantifying the contribution of these factors on speech recognition problem is important in order to formulate a holistic and effective rehabilitation. OBJECTIVE: To examine the relative contributions of auditory functioning and cognition status to speech recognition in quiet and in noise. METHODS: We measured speech recognition in quiet and in composite noise using the Malay Hearing in noise test on 72 native Malay speakers (60-82 years) older adults with normal to mild hearing loss. Auditory function included pure tone audiogram, gaps-in-noise, and dichotic digit tests. Cognitive function was assessed using the Malay Montreal cognitive assessment. RESULTS: Linear regression analyses using backward elimination technique revealed that had the better ear four frequency average (0.5-4kHz) (4FA), high frequency average and Malay Montreal cognitive assessment attributed to speech perception in quiet (total r2=0.499). On the other hand, high frequency average, Malay Montreal cognitive assessment and dichotic digit tests contributed significantly to speech recognition in noise (total r2=0.307). Whereas the better ear high frequency average primarily measured the speech recognition in quiet, the speech recognition in noise was mainly measured by cognitive function. CONCLUSIONS: These findings highlight the fact that besides hearing sensitivity, cognition plays an important role in speech recognition ability among older adults, especially in noisy environments. Therefore, in addition to hearing aids, rehabilitation, which trains cognition, may have a role in improving speech recognition in noise ability of older adults.

Speech understanding and listening effort in cochlear implant users - microphone beamformers lead to significant improvements in noisy environments.

Objectives: To evaluate the effect of microphone directionality, i.e. beamforming, on speech understanding in noise with the SONNET audio processor.Methods: Speech reception thresholds (SRTs) were tested in three different microphone settings (omnidirectional, adaptive, and fixed beamformer (natural)) and assessed via the Oldenburg Sentence Test and the Just Understanding Speech Test. Subjects rated the listening effort needed to understand speech in different signal-to-noise ratios (-10, -5, 0, 5, 10, 15 dB SNR) via a Visual Analogue Scale. For all test methods, speech was presented at 0° azimuth while fixed and uncorrelated masking noise was presented simultaneously from five loudspeakers positioned at ±70°, ±135°, and 180° azimuth.Results: Compared to the omnidirectional mode, significant improvements (p<0.001) were shown in mean SRTs for both the natural (3.3 dB SNR) and adaptive (5.2 dB SNR) settings. Using the natural or the adaptive setting required significantly less listening effort than using the omnidirectional setting for the SNR conditions -5 dB SNR (p=0.002) and 0 dB SNR (p<0.001).Discussion: The beamformer settings significantly improved speech understanding in noise over the omnidirectional setting. Due our multi-speaker test setup, we conclude that beamforming should yield significantly better and less stressful speech understanding in demanding real-life listening situations.

The development of the listening in spatialised noise - universal test (LiSN-U) and preliminary evaluation in English-speaking listeners.

Objective: To create a language independent version of the Listening in Spatialised Noise - Sentences test (LiSN-S) and evaluate it in an English-speaking population.Design: Test development and normative data collection. LiSN-Universal (LiSN-U) targets consisted of CVCV pseudo-words (e.g. /mupa/). Two looped distracter tracks consisted of CVCVCVCV pseudo-words. The listener's task was to repeat back the target pseudo-words. Stimuli were presented over headphones using an iPad. Speech reception thresholds were measured adaptively. In the co-located condition all stimuli came from directly in front. In the spatially-separated condition the distracters emanated from +90° and -90° azimuth. Perceived location was manipulated using head-related transfer functions. Spatial advantage was calculated as the difference in dB between the co-located and spatially separated conditions.Study samples: Stimulus intelligibility data were collected from 20 adults. Normative data were collected from native English speakers (23 adults and 127 children).Results: Children's spatially separated, co-located, and spatial advantage results improved significantly with age. Spatial advantage was 4-6 dB larger in the LiSN-U than LiSN-S depending on age group.Conclusion: Whereas additional research in non-native English populations is required, the LiSN-U appears to be an effective tool for measuring spatial processing ability.

The effect of room acoustical parameters on speech reception thresholds and spatial release from masking.

In daily life, speech intelligibility is affected by masking caused by interferers and by reverberation. For a frontal target speaker and two interfering sources symmetrically placed to either side, spatial release from masking (SRM) is observed in comparison to frontal interferers. In this case, the auditory system can make use of temporally fluctuating interaural time/phase and level differences promoting binaural unmasking (BU) and better-ear glimpsing (BEG). Reverberation affects the waveforms of the target and maskers, and the interaural differences, depending on the spatial configuration and on the room acoustical properties. In this study, the effect of room acoustics, temporal structure of the interferers, and target-masker positions on speech reception thresholds and SRM was assessed. The results were compared to an optimal better-ear glimpsing strategy to help disentangle energetic masking including effects of BU and BEG as well as informational masking (IM). In anechoic and moderate reverberant conditions, BU and BEG contributed to SRM of fluctuating speech-like maskers, while BU did not contribute in highly reverberant conditions. In highly reverberant rooms a SRM of up to 3 dB was observed for speech maskers, including effects of release from IM based on binaural cues.

Relationship between cochlear mechanics and speech-in-noise reception performance.

Some normal-hearing listeners report difficulties in speech perception in noisy environments, and the cause is not well understood. The present study explores the correlation between speech-in-noise reception performance and cochlear mechanical characteristics, which were evaluated using a principal component analysis of the otoacoustic emission (OAE) spectra. A principal component, specifically a characteristic dip at around 2-2.5 kHz in OAE spectra, correlated with speech reception thresholds in noise but not in quiet. The results suggest that subclinical cochlear dysfunction specifically contributes to difficulties in speech perception in noisy environments, which is possibly a new form of "hidden hearing deficits."

The Contribution of Individual Differences in Memory Span and Language Ability to Spatial Release From Masking in Young Children.

Purpose Working memory capacity and language ability modulate speech reception; however, the respective roles of peripheral and cognitive processing are unclear. The contribution of individual differences in these abilities to utilization of spatial cues when separating speech from informational and energetic masking backgrounds in children has not yet been determined. Therefore, this study explored whether speech reception in children is modulated by environmental factors, such as the type of background noise and spatial configuration of target and noise sources, and individual differences in the cognitive and linguistic abilities of listeners. Method Speech reception thresholds were assessed in 39 children aged 5-7 years in simulated school listening environments. Speech reception thresholds of target sentences spoken by an adult male consisting of number and color combinations were measured using an adaptive procedure, with speech-shaped white noise and single-talker backgrounds that were either collocated (target and back-ground at 0°) or spatially separated (target at 0°, background noise at 90° to the right). Spatial release from masking was assessed alongside memory span and expressive language. Results and Conclusion Significant main effect results showed that speech reception thresholds were highest for informational maskers and collocated conditions. Significant interactions indicated that individual differences in memory span and language ability were related to spatial release from masking advantages. Specifically, individual differences in memory span and language were related to the utilization of spatial cues in separated conditions. Language differences were related to auditory stream segregation abilities in collocated conditions that lack helpful spatial cues, pointing to the utilization of language processes to make up for losses in spatial information.

A psychoacoustic application for the adjustment of electrical hearing thresholds in cochlear implant patients.

OBJECTIVE: Fitting cochlear implants, especially the precise determination of electrical hearing thresholds, is a time-consuming and complex task for patients as well as audiologists. Aim of the study was to develop a method that enables cochlear implant (CI) patients to determine their electrical hearing thresholds precisely and independently. Applicability and impact of this method on speech perception in noise at soft speech levels were evaluated. METHOD: An adaptive psychoacoustic procedure for precise hearing threshold determination (precT) was implemented using MatLab (MathWorks) and a graphical user interface was created. Sound signals were calibrated with a CIC4-Implant-Decoder. Study design: A prospective study including 15 experienced adult cochlear implant users was conducted. Electrical hearing thresholds were determined using the automated precT procedure (auto-precT). Speech perception in noise at 50 dB SPL presentation levels was measured for three conditions: (P1) T-levels kept at the previously established T-levels; (P2) T-levels set to the hearing thresholds determined using auto-precT application; (P3) T-levels set 10 cu below the values determined with auto-precT. RESULTS: All subjects were able to perform the auto-precT application independently. T-levels were altered on average by an absolute value of 10.5 cu using auto-precT. Median speech reception thresholds were significantly improved from 2.5 dB SNR (P1) to 1.6 dB SNR (P2, p = 0.02). Speech perception was lowest using the globally lowered T-levels, median 2.9 dB SNR (P3, not significant compared to P1 and P2). CONCLUSION: The applicability of the developed auto-precT application was confirmed in the present clinical study. Patients benefited from adjusting previously established T-levels to the threshold levels determined by the auto-precT application. The integration of the application in the clinical fitting routine as well as a remote fitting software approach is recommended. Furthermore, future possibilities of auto-precT include the implementation of the application on tablets or smart phones.

Electric acoustic stimulation (EAS) with the Naída CI Q90 sound processor in experienced cochlear implant users.

Objectives: The benefit of using the electroacoustic functionality was tested compared to electric stimulation alone. Two different cut-off frequencies between acoustic and electric stimulation were tried. Methods: Performance and subjective preference in 10 subjects was measured with electric only and electroacoustic stimulation with two settings: a cut-off for acoustic amplification at the frequency where thresholds exceeded 70 dB and 85 dB. An overlapping setting was also tried in five participants. Results: There was a non-significant trend with a median improvement in SRT of 1.3 dB (70 dB cut-off) and 0.8 dB (85 dB cut-off) compared to the electric only condition. From nine subjects who completed the study, one preferred the 85 dB cut-off frequency, with the others preferred either a 70 dB cut-off or an overlapping setting. Discussion: Nine subjects continued to use the EAS processor after study termination because of subjective benefits. The variability in speech outcomes and subjective preference is underlining the importance of being able to manually change acoustic and electric cut-off frequencies. Conclusion: There were non-significant median group benefits from use of the acoustic component for these existing CI users. A hearing loss of 70 dB HL is an appropriate default cut-off frequency in the fitting software.

Low-Frequency Pitch Perception in Cochlear Implant Recipients With Normal Hearing in the Contralateral Ear.

Purpose Three experiments were carried out to evaluate the low-frequency pitch perception of adults with unilateral hearing loss who received a cochlear implant (CI). Method Participants were recruited from a cohort of CI users with unilateral hearing loss and normal hearing in the contralateral ear. First, low-frequency pitch perception was assessed for the 5 most apical electrodes at 1, 3, 6, and 12 months after CI activation using an adaptive pitch-matching task. Participants listened with a coding strategy that presents low-frequency temporal fine structure (TFS) and compared the pitch to that of an acoustic target presented to the normal hearing ear. Next, participants listened with an envelope-only, continuous interleaved sampling strategy. Pitch perception was compared between coding strategies to assess the influence of TFS cues on low-frequency pitch perception. Finally, participants completed a vocal pitch-matching task to corroborate the results obtained with the adaptive pitch-matching task. Results Pitch matches roughly corresponded to electrode center frequencies (CFs) in the CI map. Adaptive pitch matches exceeded the CF for the most apical electrode, an effect that was larger for continuous interleaved sampling than TFS. Vocal pitch matches were variable but correlated with the CF of the 3 most apical electrodes. There was no evidence that pitch matches changed between the 1- and 12-month intervals. Conclusions Relatively accurate and asymptotic pitch perception was observed at the 1-month interval, indicating either very rapid acclimatization or the provision of familiar place and rate cues. Early availability of appropriate pitch cues could have played a role in the early improvements in localization and masked speech recognition previously observed in this cohort. Supplemental Material https://doi.org/10.23641/asha.8862389.

Benefit of directional microphones for unilateral, bilateral and bimodal cochlear implant users.

OBJECTIVE: To compare the standard T-Mic setting to UltraZoom and StereoZoom in 10 unilateral cochlear implant (CI) users, 10 bimodal device users and 10 bilateral CI users as well as a normal hearing (NH) reference group (n = 10). METHOD: Speech reception thresholds were measured using the Oldenburg sentence test in noise. Speech was presented from the front at 0°, noise was presented from five loudspeakers spaced at ±60°, ±120°, 180° (setup A) or from four loudspeakers in the front hemisphere at ±30°, ±60° and one at 180° (setup B). RESULTS: There was a significant advantage for UltraZoom and StereoZoom for all groups in both setups. The largest advantage was for StereoZoom in the bilateral group (setup A, 5.2 dB, P < 0.001 and B, 3.4 dB, P < 0.001) There was a significant advantage for StereoZoom over UltraZoom in the bimodal group (setup A, P < 0.01 and B, P < 0.05) and in the bilateral group (P < 0.01, setup B only). The bilateral group performed as well as the normally hearing group in both setups and the bimodal group performed as well in setup A. There was a significant benefit of 1.8 dB for ClearVoice over UltraZoom alone for the unilateral group. CONCLUSIONS: UltraZoom and StereoZoom provided a clinically and statistically significant benefit over the T-Mic condition. The largest gain was shown for StereoZoom in the bimodal and bilateral groups. The use of StereoZoom enabled the bilateral group to perform as well as the normally hearing group in both the challenging speaker setups. However, real life environments might provide an even greater challenge than the conditions tested here.

Auditory event-related potentials and function of the medial olivocochlear efferent system in children with auditory processing disorders.

OBJECTIVE: The objectives were to investigate the function of central auditory pathways and of the medial efferent olivocochlear system (MOCS). DESIGN: Event-related potentials (ERP) were recorded following the delivery of the stimulus /da/ in quiet and in ipsilateral, contralateral, and binaural noise conditions and correlated to the results of the auditory processing disorders (APD) diagnostic test battery. MOCS function was investigated by adding ipsilateral, contralateral, and binaural noise to transient evoked otoacoustic emission recordings. Auditory brainstem responses and pure tone audiogram were also evaluated. STUDY SAMPLE: Nineteen children (7 to 12 years old) with APD were compared with 24 age-matched controls. RESULTS: Otoacoustic emissions and ABR characteristics did not differ between groups, whereas ERP latencies were significantly longer and of higher amplitudes in APD children than in controls, in both quiet and noise conditions. The MOCS suppression was higher in APD children. CONCLUSIONS: Findings indicate that children with APD present with neural deficiencies in both challenging and nonchallenging environments with an increase in the timing of several central auditory processes correlated to their behavioural performances. Meanwhile, their modulation of the auditory periphery under noisy conditions differs from control children with higher suppression.

Clinical Assessment of Functional Hearing Deficits: Speech-in-Noise Performance.

OBJECTIVE: The clinical evaluation of hearing loss, using a pure-tone audiogram, is not adequate to assess the functional hearing capabilities (or handicap) of a patient, especially the speech-in-noise communication difficulties. The primary objective of this study was to measure the effect of elevated hearing thresholds on the recognition performance in various functional speech-in-noise tests that cover acoustic scenes of different complexities and to identify the subset of tests that (a) were sensitive to individual differences in hearing thresholds and (b) provide complementary information to the audiogram. A secondary goal was to compare the performance on this test battery with the self-assessed performance level of functional hearing abilities. DESIGN: In this study, speech-in-noise performance of normal-hearing listeners and listeners with hearing loss (audiometric configuration ranging from near-normal hearing to moderate-severe hearing loss) was measured on a battery of 12 different tests designed to evaluate speech recognition in a variety of speech and masker conditions, and listening tasks. The listening conditions were designed to measure the ability to localize and monitor multiple speakers or to take advantage of masker modulation, spatial separation between the target and the masker, and a restricted vocabulary. RESULTS: Listeners with hearing loss had significantly worse performance than the normal-hearing control group when speech was presented in the presence of a multitalker babble or in the presence of a single competing talker. In particular, the ability to take advantage of modulation benefit and spatial release from masking was significantly affected even with a mild audiometric loss. Elevated thresholds did not have a significant effect on the performance in the spatial awareness task. A composite score of all 12 tests was considered as a global metric of the overall speech-in-noise performance. Perceived hearing difficulties of subjects were better correlated with the composite score than with the performance on a standardized clinical speech-in-noise test. Regression analysis showed that scores from a subset of these tests, which could potentially take less than 10 min to administer, when combined with the better-ear pure-tone average and the subject's age, accounted for as much as 93.2% of the variance in the composite score. CONCLUSIONS: A test that measures speech recognition in the presence of a spatially separated competing talker would be useful in measuring suprathreshold speech-in-noise deficits that cannot be readily predicted from standard audiometric evaluation. Including such a test can likely reduce the gap between patient complaints and their clinical evaluation.

Language-Independent Hearing Screening Based on Masked Recognition of Ecological Sounds.

A language-independent automated self-test on tablet based on masked recognition of ecological sounds, the Sound Ear Check (SEC), was developed. In this test, 24 trials of eight different sounds are randomly presented in a noise that was spectrally shaped according to the average frequency spectra of the stimulus sounds, using a 1-up 2-down adaptive procedure. The test was evaluated in adults with normal hearing and hearing loss, and its feasibility was investigated in young children, who are the target population of this test. Following equalization of perceptual difficulty across sounds by applying level adjustments to the individual tokens, a reference curve with a steep slope of 18%/dB was obtained, resulting in a test with a high test-retest reliability of 1 dB. The SEC sound reception threshold was significantly associated with the averaged pure tone threshold (r = .70), as well as with the speech reception threshold for the Digit Triplet Test (r = .79), indicating that the SEC is susceptible to both audibility and signal-to-noise ratio loss. Sensitivity and specificity values on the order of magnitude of ∼70% and ∼80% to detect individuals with mild and moderate hearing loss, respectively, and ∼80% to detect individuals with slight speech-in-noise recognition difficulties were obtained. Homogeneity among sounds was verified in children. Psychometric functions fitted to the data indicated a steep slope of 16%/dB, and test-retest reliability of sound reception threshold estimates was 1.3 dB. A reference value of -9 dB signal-to-noise ratio was obtained. Test duration was around 6 minutes, including training and acclimatization.

Pupil Responses of Adults With Traumatic Brain Injury During Processing of Speech in Noise.

Previous research has shown the effects of task demands on pupil responses in both normal hearing (NH) and hearing impaired (HI) adults. One consistent finding is that HI listeners have smaller pupil dilations at low levels of speech recognition performance (≤50%). This study aimed to examine the pupil dilation in adults with a normal pure-tone audiogram who experience serious difficulties when processing speech-in-noise. Hence, 20 adults, aged 26 to 62 years, with traumatic brain injury (TBI) or cerebrovascular accident (CVA) but with a normal audiogram participated. Their pupil size was recorded while they listened to sentences masked by fluctuating noise or interfering speech at 50% and 84% intelligibility. In each condition, participants rated their perceived performance, effort, and task persistence. In addition, participants performed the text reception threshold task-a visual sentence completion task-that measured language-related processing. Data were compared with those of age-matched NH and HI participants with no neurological problems obtained in earlier studies using the same setup and design. The TBI group had the same pure-tone audiogram and text reception threshold scores as the NH listeners, yet their speech reception thresholds were significantly worse. Although the pupil dilation responses on average did not differ between groups, self-rated effort scores were highest in the TBI group. Results of a correlation analyses showed that TBI participants with worse speech reception thresholds had a smaller pupil response. We speculate that increased distractibility or fatigue affected the ability of TBI participants to allocate effort during speech perception in noise.

Data-Driven Approach for Auditory Profiling and Characterization of Individual Hearing Loss.

Pure-tone audiometry still represents the main measure to characterize individual hearing loss and the basis for hearing-aid fitting. However, the perceptual consequences of hearing loss are typically associated not only with a loss of sensitivity but also with a loss of clarity that is not captured by the audiogram. A detailed characterization of a hearing loss may be complex and needs to be simplified to efficiently explore the specific compensation needs of the individual listener. Here, it is hypothesized that any listener's hearing profile can be characterized along two dimensions of distortion: Type I and Type II. While Type I can be linked to factors affecting audibility, Type II reflects non-audibility-related distortions. To test this hypothesis, the individual performance data from two previous studies were reanalyzed using an unsupervised-learning technique to identify extreme patterns in the data, thus forming the basis for different auditory profiles. Next, a decision tree was determined to classify the listeners into one of the profiles. The analysis provides evidence for the existence of four profiles in the data. The most significant predictors for profile identification were related to binaural processing, auditory nonlinearity, and speech-in-noise perception. This approach could be valuable for analyzing other data sets to select the most relevant tests for auditory profiling and propose more efficient hearing-deficit compensation strategies.

Categorization of sentence recognition for older adults under noisy and time-altered conditions.

PURPOSE: While evaluating the speech recognition ability of older adults, the present study aimed to analyze their error types in parts of speech and find error patterns under various conditions of background noise level and speed of speech. METHODS: Twenty older adults with normal hearing for their age (NHiA) and 20 older adults with sensorineural hearing loss (SNHL) participated. Their cognitive function was screened as within the normal range (mini-mental state examination scores >25). The SNHL listeners were divided into high performers (SNHL-H; n=12) and low performers (SNHL-L; n=8), based on their achieving word recognition scores above or below 70%, respectively. A sentence recognition test was conducted at four levels of signal-to-noise ratio (SNR; eg, no noise, +6, +3, 0 dB) and four conditions of time alteration (eg, 30% and 15% of compression and expansion) at the most comfortable level for each participant. RESULTS: As expected, the three groups showed that the error percentage increased in sentence recognition as either the SNR decreased or the speech rate became faster. Interestingly, a larger performance difference was found between the SNHL-H and SNHL-L groups in the condition of time alteration than in that of background noise. Among the parts of speech, nouns presented the highest error scores for all participants regardless of degree of listening difficulty. The noun errors of the three groups mainly consisted of no response and fail patterns, but substitution and omission were identified as the third pattern of noun error for background noise and fast speech, respectively. CONCLUSION: Deterioration of speech recognition from the hearing threshold and supra-threshold auditory processing was seen in the elderly in difficult listening environments such as background noise and time alteration. Although different group performance ran across the eight experimental conditions, the robustness of noun errors and the error patterns were very similar, which might be extended to a possible clinical application of aural rehabilitation for the elderly population.

Effects of Slow- and Fast-Acting Compression on Hearing-Impaired Listeners' Consonant-Vowel Identification in Interrupted Noise.

There is conflicting evidence about the relative benefit of slow- and fast-acting compression for speech intelligibility. It has been hypothesized that fast-acting compression improves audibility at low signal-to-noise ratios (SNRs) but may distort the speech envelope at higher SNRs. The present study investigated the effects of compression with a nearly instantaneous attack time but either fast (10 ms) or slow (500 ms) release times on consonant identification in hearing-impaired listeners. Consonant-vowel speech tokens were presented at a range of presentation levels in two conditions: in the presence of interrupted noise and in quiet (with the compressor "shadow-controlled" by the corresponding mixture of speech and noise). These conditions were chosen to disentangle the effects of consonant audibility and noise-induced forward masking on speech intelligibility. A small but systematic intelligibility benefit of fast-acting compression was found in both the quiet and the noisy conditions for the lower speech levels. No detrimental effects of fast-acting compression were observed when the speech level exceeded the level of the noise. These findings suggest that fast-acting compression provides an audibility benefit in fluctuating interferers when compared with slow-acting compression while not substantially affecting the perception of consonants at higher SNRs.

Construction and evaluation of the Mandarin Chinese matrix (CMNmatrix) sentence test for the assessment of speech recognition in noise.

OBJECTIVE: Development of the Mandarin Chinese matrix (CMNmatrix) sentence test for speech intelligibility measurements in noise according to the international standard procedure. DESIGN: A 50-word base matrix representing the distribution of phonemes and lexical tones of spoken Mandarin was established. Hundred sentences capturing all the co-articulations of two consecutive words were recorded. Word-specific speech recognition functions, speech reception thresholds (SRT: signal-to-noise ratio (SNR), that provides 50% speech intelligibility) and slopes were obtained from measurements at fixed SNRs. The speech material was homogenised in intelligibility by applying level corrections up to ± 2 dB. Subsequently, the CMNmatrix test was evaluated, the comparability of test lists was measured at two fixed SNRs. To investigate the training effect and establish the reference data, speech recognition was measured adaptively. STUDY SAMPLE: Overall, the study sample contained 80 normal-hearing native Mandarin-speaking listeners. RESULTS: Multi-centre evaluation measurements confirmed that test lists are equivalent in intelligibility, with a mean SRT of -10.1 ± 0.1 dB SNR and a slope of 13.1 ± 0.9 %/dB. The reference SRT is -9.3 ± 0.8 and -11.2 ± 1.2 dB SNR for the open- and closed-set response format, respectively. CONCLUSION: The CMNmatrix test is suitable for accurate and internationally comparable speech recognition measurements in noise.