Development of the Russian matrix sentence test

Objective: To develop the Russian matrix sentence test for speech intelligibility measurements in noise. Design: Test development included recordings, optimization of speech material, and evaluation to investigate the equivalency of the test lists and training. For each of the 500 test items, the speech intelligibility function, speech reception threshold (SRT: signal-to-noise ratio, SNR, that provides 50% speech intelligibility), and slope was obtained. The speech material was homogenized by applying level corrections. In evaluation measurements, speech intelligibility was measured at two fixed SNRs to compare list-specific intelligibility functions. To investigate the training effect and establish reference data, speech intelligibility was measured adaptively. Study sample: Overall, 77 normal-hearing native Russian listeners. Results: The optimization procedure decreased the spread in SRTs across words from 2.8 to 0.6 dB. Evaluation measurements confirmed that the 16 test lists were equivalent, with a mean SRT of ? 9.5 ± 0.2 dB and a slope of 13.8 ± 1.6%/dB. The reference SRT, ? 8.8 ± 0.8 dB for the open-set and ? 9.4 ± 0.8 dB for the closed-set format, increased slightly for noise levels above 75 dB SPL. Conclusions: The Russian matrix sentence test is suitable for accurate and reliable speech intelligibility measurements in noise.     

Influence of noise type on speech reception thresholds across four languages measured with matrix sentence tests

Objective: To compare speech reception thresholds (SRTs) in noise using matrix sentence tests in four languages: German, Spanish, Russian, Polish. Design: The four tests were composed of equivalent five-word sentences and were all designed and optimized using the same principles. Six stationary speech-shaped noises and three non-stationary noises were used as maskers. Study sample: Forty native listeners with normal hearing: 10 for each language. Results: SRTs were about 3 dB higher for the German and Spanish tests than for the Russian and Polish tests when stationary noise was used that matched the long-term frequency spectrum of the respective speech test materials. This general SRT difference was also observed for the other stationary noises. The within-test variability across noise conditions differed between languages. About 56% of the observed variance was predicted by the speech intelligibility index. The observed SRT benefit in fluctuating noise was similar for all tests, with a slightly smaller benefit for the Spanish test. Conclusions: Of the stationary noises employed, noise with the same spectrum as the speech yielded the best masking. SRT differences across languages and noises could be attributed in part to spectral differences. These findings provide the feasibility and limits of comparing audiological results across languages.     

Development and evaluation of the Turkish matrix sentence test

Objectives: The Turkish matrix sentence test, TURMatrix, was developed for precise, internationally comparable speech intelligibility testing. Design: The TURMatrix comprises a base matrix of ten well-known Turkish names, numbers, adjectives, objects, verbs, from which syntactically fixed sentences were randomly composed. Test conduction may be in an open-set (standard), or closed-set response format. Homogeneity in intelligibility of the test material was optimized by applying level adaptations (maximal ± 3 dB) based on word-specific speech reception thresholds (SRTs). Test list equivalence was verified and reference values were determined. Study sample: Thirty-eight native listeners of Turkish with normal hearing. Results: After training, mean SRT and slope of the final test lists were ? 8.3 ± 0.2 dB SNR and 14.1 ± 1.0%/dB, respectively (fixed SNR measurements; inter-list variability). For adaptive measurements, average across listeners was ? 7.2 ± 0.7 dB SNR in the open-set and ? 7.9 ± 0.7 dB SNR in the closed-set response format. Mean SRT for adaptive measurements in the open-set response format in quiet was 20.3 ± 4.1 dB. Individual SRTs in quiet correlated more closely with audiograms than with SRTs in noise. Conclusions: The TURMatrix was developed according to European standards and provides reliable speech intelligibility measurements in noise and quiet.     

Talker- and language-specific effects on speech intelligibility in noise assessed with bilingual talkers: Which language is more robust against noise and reverberation?

Objective: Investigate talker- and language-specific aspects of speech intelligibility in noise and reverberation using highly comparable matrix sentence tests across languages. Design: Matrix sentences spoken by German/Russian and German/Spanish bilingual talkers were recorded. These sentences were used to measure speech reception thresholds (SRTs) with native listeners in the respective languages in different listening conditions (stationary and fluctuating noise, multi-talker babble, reverberated speech-in-noise condition). Study sample: Four German/Russian and four German/Spanish bilingual talkers; 20 native German-speaking, 10 native Russian-speaking, and 10 native Spanish-speaking listeners. Results: Across-talker SRT differences of up to 6 dB were found for both groups of bilinguals. SRTs of German/Russian bilingual talkers were the same in both languages. SRTs of German/Spanish bilingual talkers were higher when they talked in Spanish than when they talked in German. The benefit from listening in the gaps was similar across all languages. The detrimental effect of reverberation was larger for Spanish than for German and Russian. Conclusions: Within the limitations set by the number and slight accentedness of talkers and other possible confounding factors, talker- and test-condition-dependent differences were isolated from the language effect: Russian and German exhibited similar intelligibility in noise and reverberation, whereas Spanish was more impaired in these situations.     

Validation of a French translation of the speech,spatial, and qualities of hearing scale (SSQ) and comparison with other language versions

Objective: To validate a French version of the speech, spatial, and qualities of hearing scale (SSQ), a subjective evaluation of patients’ hearing disability, and to assess SSQ reproducibility across different language versions. Design: The SSQ was translated in accordance with the principles of the ‘Universalist approach’ of cross-cultural adaptation of patient-reported outcome instruments. Scores from a normal-hearing and a hearing-impaired population were compiled and compared, whenever possible, with data from the literature, collected using other language versions. Study sample: One hundred normal-hearing subjects and 230 hearing-impaired subjects. Results: Good reproducibility of scores and inter-subject variability were obtained between several language versions, even if scores found using the French version were slightly lower than those obtained using Dutch or English versions. A comparison of factor analysis outcomes between the English and French versions confirmed good conceptual equivalence across languages and robustness of the SSQ for use in international settings. The three main subscales (speech, spatial, and qualities) confirmed their usefulness in assessing different aspects of hearing disability. Conclusion: This study validated a French-language version of the SSQ, and assessed the reproducibility of the SSQ across subject groups, administration modes, and different countries/languages, confirming its potential as an international standard for hearing disability evaluation.     

Internationally comparable screening tests for listening in noise in several European languages: The German digit triplet test as an optimization prototype

Abstract

Objective: A review is given of internationally comparable speech-in-noise tests for hearing screening purposes that were part of the European HearCom project. This report describes the development, optimization, and evaluation of such tests for headphone and telephone presentation, using the example of the German digit triplet test. In order to achieve the highest possible comparability, language- and speaker-dependent factors in speech intelligibility should be compensated for. Materials and methods: The tests comprise spoken numbers in background noise and estimate the speech reception threshold (SRT), i.e. the signal-to-noise ratio (SNR) yielding 50% speech intelligibility. Results: The respective reference speech intelligibility functions for headphone and telephone presentation of the German version for 15 and 10 normal-hearing listeners are described by a SRT of ?9.3?±?0.2 and ?6.5?±?0.4 dB SNR, and slopes of 19.6 and 17.9%/dB, respectively. Reference speech intelligibility functions of all digit triplet tests optimized within the HearCom project allow for investigation of the comparability due to language specificities. Conclusions: The optimization criteria established here should be used for similar screening tests in other languages.     

Development of a Dutch matrix sentence test to assess speech intelligibility in noise

Abstract

Objective: A Dutch matrix sentence test was developed and evaluated. A matrix test is a speech-in-noise test based on a closed speech corpus of sentences derived from words from fixed categories. An example is “Mark gives five large flowers.” Design: This report consists of the development of the speech test and a multi-center evaluation. Study sample: Forty-five normal-hearing participants. Results: The developed matrix test has a speech reception threshold in stationary noise of ? 8.4 dB with an inter-list standard deviation of 0.2 dB. The slope of the intelligibility function is 10.2 %/dB and this is slightly lower than that of similar tests in other languages (12.6 to 17.1 %/dB). Conclusions: The matrix test is now also available in Dutch and can be used in both Flanders and the Netherlands.     

An Italian matrix sentence test for the evaluation of speech intelligibility in noise

Objective: Development of an Italian matrix sentence test for the assessment of speech intelligibility in noise. Design: The development of the test included the selection, recording, optimization with level adjustment, and evaluation of speech material. The training effect was assessed adaptively during the evaluation measurements with six lists of 20 sentences, using open- and closed-set response formats. Reference data were established for normal-hearing listeners with adaptive measurements. Equivalence of the test lists was investigated using the open-set response format at three signal-to-noise ratios (SNRs). Study sample: A total of 55 normal-hearing Italian mother-tongue listeners. Results: The evaluation measurements at fixed SNRs resulted in a mean speech reception threshold (SRT) of ? 7.3 ± 0.2 dB SNR and slope of 13.3 ± 1.2 %/dB. The major training effect of 1.5 dB was observed for the first two consecutive measurements. Mean SRTs of ? 6.7 ± 0.7 dB SNR and ? 7.4 ± 0.7 dB SNR were found from the third to the sixth adaptive measurement for open- and closed-set test response formats, respectively. Conclusions: A good agreement has been found between the SRTs and slope and those of other matrix tests. Since sentences are difficult to memorize, the Italian matrix test is suitable for repeated measurements.     

Acoustic simulation of cochlear implant hearing: Effect of manipulating various acoustic parameters on intelligibility of speech

Objective: Cochlear implants process the acoustic speech signal and convert it into electrical impulses. During this processing, many parameters contribute to speech perception. The available literature reviewed the effect of manipulating one or two such parameters on speech intelligibility, but multiple parameters are seldom manipulated.

Method: Acoustic parameters, including pulse rate, number of channels, ‘n of m’, number of electrodes, and channel spacing, were manipulated in acoustic simulations of cochlear implant hearing and 90 different combinations were created. Speech intelligibility at sentence level was measured using subjective and objective tests.

Results: Principal component analysis was employed to select only those components with maximum factor loading, thus reducing the number of components to a reasonable limit. Perceptual speech intelligibility was maximum for signal processing manipulation with respect to ‘n of m’ and rate of pulses/sec. Regression analysis revealed that lower rate (=500?pps/ch) and lesser stimulating electrodes per cycle (2–4) contributed maximally for speech intelligibility. Perceptual estimate of speech quality (PESQ) and composite measures of spectral weights and likelihood ratio correlated with subjective speech intelligibility scores.

Discussion: The findings are consistent with the literature review, indicating that lesser stimulated channel per cycle reduces electrode interaction and hence improve spectral resolution of speech. Reduced rate of pulses/second enhances temporal resolution of speech. Thus, these two components contribute significantly to speech intelligibility.

Conclusion: Pulse rate/channel and ‘n of m’ contribute maximally to speech intelligibility, at least in simulations of electric hearing.     

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

Abstract

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.     

Semantic context improves speech intelligibility and reduces listening effort for listeners with hearing impairment

Objective: We investigated whether speech intelligibility and listening effort for hearing-aid users is affected by semantic context and hearing-aid setting. Design: Participants heard target sentences spoken in a reverberant background of cafeteria noise and competing speech. Participants reported each sentence verbally. Eight participants also rated listening effort after each sentence. Sentence topic was either the same as, or different from, the previous target sentence. Study sample: Twenty participants with sensorineural hearing loss were fit binaurally with Signia receiver-in-the-canal hearing aids. Participants performed the task twice: once using the hearing aid’s omnidirectional setting and once using the “Reverberant Room” setting, designed to aid listening in reverberant environments. Results: Participants achieved better speech intelligibility for same-topic than different-topic sentences, and when they used the “Reverberant Room” than the omnidirectional hearing-aid setting. Participants who rated effort showed a reliable reduction in listening effort for same-topic sentences and for the “Reverberant Room” hearing-aid setting. The improvement in speech intelligibility from semantic context (i.e. same-topic compared to different-topic sentences) was greater than the improvement gained from changing hearing-aid setting. Conclusions: These findings highlight the enormous potential of cognitive (specifically, semantic) factors for improving speech intelligibility and reducing perceived listening effort in noise for hearing-aid users.     

A Spanish matrix sentence test for assessing speech reception thresholds in noise

Objective: To develop, optimize, and evaluate a new Spanish sentence test in noise. Design: The test comprises a basic matrix of ten names, verbs, numerals, nouns, and adjectives. From this matrix, test lists of ten sentences with an equal syntactical structure can be formed at random, with each list containing the whole speech material. The speech material represents the phoneme distribution of the Spanish language. The test was optimized for measuring speech reception thresholds (SRTs) in noise by adjusting the presentation levels of the individual words. Subsequently, the test was evaluated by independent measurements investigating the training effects, the comparability of test lists, open-set vs. closed-set test format, and performance of listeners of different Spanish varieties. Study sample: In total, 68 normal-hearing native Spanish-speaking listeners. Results: SRTs measured using an adaptive procedure were 6.2 ± 0.8 dB SNR for the open-set and 7.2 ± 0.7 dB SNR for the closed-set test format. The residual training effect was less than 1 dB after using two double-lists before data collection. Conclusions: No significant differences were found for listeners of different Spanish varieties indicating that the test is applicable to Spanish as well as Latin American listeners. Test lists can be used interchangeably.     

Speech intelligibility of virtual humans

Abstract

The speech intelligibility benefit of visual speech cues during oral communication is well-established. Therefore, an ecologically valid approach of auditory assessment should include the processing of both auditory and visual speech cues. This study describes the development and evaluation of a virtual human speaker designed to present speech auditory-visually. A male and female virtual human speaker were created and evaluated in two experiments: a visual-only speech reading test of words and sentences and an auditory-visual speech intelligibility sentence test. A group of five hearing, skilled speech reading adults participated in the speech reading test whereas a group of young normal-hearing participants (N?=?35) was recruited for the intelligibility test. Skilled speech readers correctly identified 57 to 67% of the words and sentences uttered by the virtual speakers. The presence of the virtual speaker improved the speech intelligibility of sentences in noise by 1.5 to 2?dB. These results demonstrate the potential applicability of virtual humans in future auditory-visual speech assessment paradigms.     

International Collegium of Rehabilitative Audiology (ICRA) recommendations for the construction of multilingual speech tests

Objective: To provide guidelines for the development of two types of closed-set speech-perception tests that can be applied and interpreted in the same way across languages. The guidelines cover the digit triplet and the matrix sentence tests that are most commonly used to test speech recognition in noise. They were developed by a working group on Multilingual Speech Tests of the International Collegium of Rehabilitative Audiology (ICRA). Design: The recommendations are based on reviews of existing evaluations of the digit triplet and matrix tests as well as on the research experience of members of the ICRA Working Group. They represent the results of a consensus process. Results: The resulting recommendations deal with: Test design and word selection; Talker characteristics; Audio recording and stimulus preparation; Masking noise; Test administration; and Test validation. Conclusions: By following these guidelines for the development of any new test of this kind, clinicians and researchers working in any language will be able to perform tests whose results can be compared and combined in cross-language studies.     

Polish sentence tests for measuring the intelligibility of speech in interfering noise

The aim of this study was to develop Polish sentence tests for accurate measuring of speech intelligibility in masking interfering noise. Two sets of sentence lists have been developed. The first set was composed of 25 lists and was used for sentence intelligibility scoring. The second set was composed of 22 lists and was used for word intelligibility scoring. The lists in each set have been phonemically and statistically balanced. The speech reception threshold (SRT) and slope of the psychometric function at the SRT point (S₅₀) were determined in normal-hearing subjects. It was found that the mean SRT and mean list-specific S_50list for the first set were equal to ?6.1 dB and 25.5%/dB, respectively. The mean SRT and the mean list-specific S_50list for the second set were:?7.5 dB and 20.8%/dB. Due to a relatively steep slope of the psychometric functions, the Polish sentence tests were shown to be accurate materials for speech intelligibility measurements against interfering noise. They are the first sentence speech-in-noise tests developed for Slavonic languages.     

Development of equally intelligible Telugu sentence-lists to test speech recognition in noise

Objective: To develop sentence lists in the Telugu language for the assessment of speech recognition threshold (SRT) in the presence of background noise through identification of the mean signal-to-noise ratio required to attain a 50% sentence recognition score (SRTn). Design: This study was conducted in three phases. The first phase involved the selection and recording of Telugu sentences. In the second phase, 20 lists, each consisting of 10 sentences with equal intelligibility, were formulated using a numerical optimisation procedure. In the third phase, the SRTn of the developed lists was estimated using adaptive procedures on individuals with normal hearing. Study sample: A total of 68 native Telugu speakers with normal hearing participated in the study. Of these, 18 (including the speakers) performed on various subjective measures in first phase, 20 performed on sentence/word recognition in noise for second phase and 30 participated in the list equivalency procedures in third phase. Results: In all, 15 lists of comparable difficulty were formulated as test material. The mean SRTn across these lists corresponded to ?2.74 (SD?=?0.21). Conclusions: The developed sentence lists provided a valid and reliable tool to measure SRTn in Telugu native speakers.     

Internationally comparable screening tests for listening in noise in several European languages: The German digit triplet test as an optimization prototype

Abstract Objective: A review is given of internationally comparable speech-in-noise tests for hearing screening purposes that were part of the European HearCom project. This report describes the development, optimization, and evaluation of such tests for headphone and telephone presentation, using the example of the German digit triplet test. In order to achieve the highest possible comparability, language- and speaker-dependent factors in speech intelligibility should be compensated for. Materials and methods: The tests comprise spoken numbers in background noise and estimate the speech reception threshold (SRT), i.e. the signal-to-noise ratio (SNR) yielding 50% speech intelligibility. Results: The respective reference speech intelligibility functions for headphone and telephone presentation of the German version for 15 and 10 normal-hearing listeners are described by a SRT of -9.3?±?0.2 and -6.5?±?0.4 dB SNR, and slopes of 19.6 and 17.9%/dB, respectively. Reference speech intelligibility functions of all digit triplet tests optimized within the HearCom project allow for investigation of the comparability due to language specificities. Conclusions: The optimization criteria established here should be used for similar screening tests in other languages.     

Development of a German reading span test with dual task design for application in cognitive hearing research

Objective: To report the development of a standardized German version of a reading span test (RST) with a dual task design. Special attention was paid to psycholinguistic control of the test items and time-sensitive scoring. We aim to establish our RST version to use for determining an individual's working memory in the framework of hearing research in German contexts. Design: RST stimuli were controlled and pretested for psycholinguistic factors. The RST task was to read sentences, quickly determine their plausibility, and later recall certain words to determine a listener's individual reading span. RST results were correlated with outcomes of additional sentence-in-noise tests measured in an aided and an unaided listening condition, each at two reception thresholds. Study sample: Item plausibility was pre-determined by 28 native German participants. An additional 62 listeners (45–86 years, M = 69.8) with mild-to-moderate hearing loss were tested for speech intelligibility and reading span in a multicenter study. Results: The reading span test significantly correlated with speech intelligibility at both speech reception thresholds in the aided listening condition. Conclusion: Our German RST is standardized with respect to psycholinguistic construction principles of the stimuli, and is a cognitive correlate of intelligibility in a German matrix speech-in-noise test.     

Matrix sentence intelligibility prediction using an automatic speech recognition system

Objective: The feasibility of predicting the outcome of the German matrix sentence test for different types of stationary background noise using an automatic speech recognition (ASR) system was studied. Design: Speech reception thresholds (SRT) of 50% intelligibility were predicted in seven noise conditions. The ASR system used Mel-frequency cepstral coefficients as a front-end and employed whole-word Hidden Markov models on the back-end side. The ASR system was trained and tested with noisy matrix sentences on a broad range of signal-to-noise ratios. Study sample: The ASR-based predictions were compared to data from the literature (Hochmuth et al, 2015 Hochmuth S., Jürgens T., Brand T. & Kollmeier B. 2015. Influence of noise type on speech reception thresholds across four languages measured with matrix sentence tests. Int J Audiol., 54, doi: 10.3109/14992027.2015.1046502. [22 June 2015][Taylor & Francis Online], [Web of Science ®] , [Google Scholar]) obtained with 10 native German listeners with normal hearing and predictions of the speech intelligibility index (SII). Results: The ASR-based predictions showed a high and significant correlation (R² = 0.95, p < 0.001) with the empirical data across different noise conditions, outperforming the SII-based predictions which showed no correlation with the empirical data (R² = 0.00, p = 0.987). Conclusions: The SRTs for the German matrix test for listeners with normal hearing in different stationary noise conditions could well be predicted based on the acoustical properties of the speech and noise signals. Minimum assumptions were made about human speech processing already incorporated in a reference-free ordinary ASR system.     

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

Objective: To develop, in Australian English, the first mixed-gender, multi-talker matrix sentence test. Design: Speech material consisted of a 50-word base matrix whose elements can be combined to form sentences of identical syntax but unpredictable content. Ten voices (five female and five male) were recorded for editing and preliminary level equalization. Elements were presented as single-talker sentences-in-noise during two perceptual tests: an optimization phase that provided the basis for further level correction, and an evaluation phase that perceptually validated those changes. Study sample: Ten listeners participated in the optimization phase; these and an additional 32?naïve listeners completed the evaluation test. All were fluent in English and all but one had lived in Australia for >2 years. Results: Optimization reduced the standard deviation (SD) and speech reception threshold (SRT) range across all speech material (grand mean SRT?=??10.6?dB signal-to-noise ratio, median?=??10.8, SD =1.4, range =13.7, slope =19.3%/dB), yielding data consistent with cross-validated matrix tests in other languages. Intelligibility differences between experienced and naïve listeners were minimal. Conclusions: The Australian matrix corpus provides a robust set of test materials suitable for both clinical assessment and research into the dynamics of active listening in multi-talker environments.