Development and evaluation of a mixed gender, multi-talker matrix sentence test in Australian English

Development and evaluation of the Cantonese matrix sentence test

OBJECTIVE

To develop the Cantonese matrix (YUEmatrix) test according to the international standard procedure and examine possible different outcomes in another tonal language.

DESIGN

A 50-word Cantonese base-matrix was established. Word-specific speech recognition functions, speech recognition thresholds (SRT), and slopes were obtained. The speech material was homogenised in intelligibility by applying level corrections up to ± 3 dB. Subsequently, the YUEmatrix test was evaluated in five aspects: training effect, test-list equivalence, test-retest reliability, establishment of reference data for normal-hearing Cantonese-speakers, and comparison with the Cantonese-Hearing-In-Noise-Test.

STUDY SAMPLE

Overall, 64 normal-hearing native Cantonese-speaking listeners.

RESULTS

SRT measurements with adaptive procedures resulted in a reference SRT of -9.7 ± 0.7 dB SNR for open-set and -11.1 ± 1.2 dB SNR for the closed-set response format. Fixed SNR measurements suggested a test-specific speech intelligibility function slope of 15.5 ± 0.7%/dB. Seventeen 10-sentences base test lists were confirmed to be equivalent with respect to speech intelligibility. Training effect was not observed after two measurements of 20-sentences lists.

CONCLUSIONS

The YUEmatrix yields comparable results to matrix tests in other languages including Mandarin. Level adjustments to homogenise sentences appear to be less effective for tonal languages than for most other languages developed so far.

The German hearing in noise test with a female talker: development and comparison with German male speech test

PURPOSE

The aim of the study was to develop the German Hearing in Noise Test (HINT) with female speaker by fulfilling the recommendations by International Collegium of Rehabilitative Audiology (ICRA) for using a female speaker to create new multilingual speech tests and to determine norms and to compare these norms with German male speech tests-the male speakers HINT and the Oldenburg Sentence Test (OLSA).

METHODS

The HINT with a female speaker consists of the same speech material as the male speaking HINT. After recording the speech material, 10 normal hearing subjects were included to determine the performance-intensity function (PI function). 24 subjects were part of the measurements to determine the norms and compare them with the norms of male HINT and OLSA. Comparably, adaptive, open-set methods under headphones (HINT) and sound field (OLSA) were used.

RESULTS

Acoustic phonetic analysis demonstrated significant difference in mean fundamental frequency, its range and mean speaking rate between both HINT speakers. The calculated norms by three of the tested four conditions of the HINT with a female speaker are not significantly different from the norms with a male speaker. No significant effect of the speaker's gender of the first HINT measurement and no significant correlation between the threshold results of the HINT and the OLSA were determined.

CONCLUSIONS

The Norms for German HINT with a female speaker are comparable to the norms of the HINT with a male speaker. The speech intelligibility score of the HINT does not depend on the speakers' gender despite significant difference of acoustic-phonetic parameters between the female and male HINT speaker's voice. Instead, the speech intelligibility rating must be seen as a function of the used speech material.

Inference of the distortion component of hearing impairment from speech recognition by predicting the effect of the attenuation component

OBJECTIVE

A model-based determination of the average supra-threshold ("distortion") component of hearing impairment which limits the benefit of hearing aid amplification.

DESIGN

Published speech recognition thresholds (SRTs) were predicted with the framework for auditory discrimination experiments (FADE), which simulates recognition processes, the speech intelligibility index (SII), which exploits frequency-dependent signal-to-noise ratios (SNR), and a modified SII with a hearing-loss-dependent band importance function (PAV). Their attenuation-component-based prediction errors were interpreted as estimates of the distortion component.

STUDY SAMPLE

Unaided SRTs of 315 hearing-impaired ears measured with the German matrix sentence test in stationary noise.

RESULTS

Overall, the models showed root-mean-square errors (RMSEs) of 7 dB, but for steeply sloping hearing loss FADE and PAV were more accurate (RMSE = 9 dB) than the SII (RMSE = 23 dB). Prediction errors of FADE and PAV increased linearly with the average hearing loss. The consideration of the distortion component estimate significantly improved the accuracy of FADE's and PAV's predictions.

CONCLUSIONS

The supra-threshold distortion component-estimated by prediction errors of FADE and PAV-seems to increase with the average hearing loss. Accounting for a distortion component improves the model predictions and implies a need for effective compensation strategies for supra-threshold processing deficits with increasing audibility loss.

Speech intelligibility in a realistic virtual sound environment

In the present study, speech intelligibility was evaluated in realistic, controlled conditions. "Critical sound scenarios" were defined as acoustic scenes that hearing aid users considered important, difficult, and common through ecological momentary assessment. These sound scenarios were acquired in the real world using a spherical microphone array and reproduced inside a loudspeaker-based virtual sound environment (VSE) using Ambisonics. Speech reception thresholds (SRT) were measured for normal-hearing (NH) and hearing-impaired (HI) listeners, using sentences from the Danish hearing in noise test, spatially embedded in the acoustic background of an office meeting sound scenario. In addition, speech recognition scores (SRS) were obtained at a fixed signal-to-noise ratio (SNR) of -2.5 dB, corresponding to the median conversational SNR in the office meeting. SRTs measured in the realistic VSE-reproduced background were significantly higher for NH and HI listeners than those obtained with artificial noise presented over headphones, presumably due to an increased amount of modulation masking and a larger cognitive effort required to separate the target speech from the intelligible interferers in the realistic background. SRSs obtained at the fixed SNR in the realistic background could be used to relate the listeners' SI to the potential challenges they experience in the real world.

Development of the Everyday Conversational Sentences in Noise test

To capture the demands of real-world listening, laboratory-based speech-in-noise tasks must better reflect the types of speech and environments listeners encounter in everyday life. This article reports the development of original sentence materials that were produced spontaneously with varying vocal efforts. These sentences were extracted from conversations between a talker pair (female/male) communicating in different realistic acoustic environments to elicit normal, raised and loud vocal efforts. In total, 384 sentences were extracted to provide four equivalent lists of 16 sentences at the three efforts for the two talkers. The sentences were presented to 32 young, normally hearing participants in stationary noise at five signal-to-noise ratios from -8 to 0 dB in 2 dB steps. Psychometric functions were fitted for each sentence, revealing an average 50% speech reception threshold (SRT₅₀) of -5.2 dB, and an average slope of 17.2%/dB. Sentences were then level-normalised to adjust their individual SRT₅₀ to the mean (-5.2 dB). The sentences may be combined with realistic background noise to provide an assessment method that better captures the perceptual demands of everyday communication.

The Effects of Switching Non-Spatial Attention During Conversational Turn Taking

This study examined the effect of a change in target voice on word recall during a multi-talker conversation. Two experiments were conducted using matrix sentences to assess the cost of a single endogenous switch in non-spatial attention. Performance in a yes-no recognition task was significantly worse when a target voice changed compared to when it remained the same after a turn-taking gap. We observed a decrease in target hit rate and sensitivity, and an increase in masker confusion errors following a change in voice. These results highlight the cognitive demands of not only engaging attention on a new talker, but also of disengaging attention from a previous target voice. This shows that exposure to a voice can have a biasing effect on attention that persists well after a turn-taking gap. A second experiment showed that there was no change in switching performance using different talker combinations. This demonstrates that switching costs were consistent and did not depend on the degree of acoustic differences in target voice characteristics.

A Competing Voices Test for Hearing-Impaired Listeners Applied to Spatial Separation and Ideal Time-Frequency Masks

People with hearing impairment find competing voices scenarios to be challenging, both with respect to switching attention from one talker to the other, as well as maintaining attention. With the Danish competing voices test (CVT) presented here, the dual-attention skills can be assessed. The CVT provides sentences spoken by three male and three female talkers, played in sentence pairs. The task of the listener is to repeat the target sentence from the sentence pair based on cueing either before or after playback. One potential way of assisting segregation of two talkers is to take advantage of spatial unmasking by presenting one talker per ear after application of time-frequency masks for separating the mixture. Using the CVT, this study evaluated four spatial conditions in 14 moderate-to-severely hearing-impaired listeners to establish benchmark results for this type of algorithm applied to hearing-impaired listeners. The four spatial conditions were as follows: summed (diotic), separate, the ideal ratio mask, and the ideal binary mask. The results show that the test is sensitive to the change in spatial condition. The temporal position of the cue has a large impact, as cueing the target talker before playback focuses the attention toward the target, whereas cueing after playback requires equal attention to the two talkers, which is more difficult. Furthermore, both applied ideal masks show test scores very close to the ideal separate spatial condition, suggesting that this technique is useful for future separation algorithms using estimated rather than ideal masks.