Sabine Hochmuth
University of Oldenburg
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Publication
Featured researches published by Sabine Hochmuth.
International Journal of Audiology | 2015
Birger Kollmeier; Anna Warzybok; Sabine Hochmuth; Melanie A. Zokoll; Verena Uslar; Thomas Brand; Kirsten C. Wagener
Objective: A review of the development, evaluation, and application of the so-called ‘matrix sentence test’ for speech intelligibility testing in a multilingual society is provided. The format allows for repeated use with the same patient in her or his native language even if the experimenter does not understand the language. Design: Using a closed-set format, the syntactically fixed, semantically unpredictable sentences (e.g. ‘Peter bought eight white ships’) provide a vocabulary of 50 words (10 alternatives for each position in the sentence). The principles (i.e. construction, optimization, evaluation, and validation) for 14 different languages are reviewed. Studies of the influence of talker, language, noise, the training effect, open vs. closed conduct of the test, and the subjects’ language proficiency are reported and application examples are discussed. Results: The optimization principles result in a steep intelligibility function and a high homogeneity of the speech materials presented and test lists employed, yielding a high efficiency and excellent comparability across languages. The characteristics of speakers generally dominate the differences across languages. Conclusion: The matrix test format with the principles outlined here is recommended for producing efficient, reliable, and comparable speech reception thresholds across different languages.
International Journal of Audiology | 2012
Sabine Hochmuth; Thomas Brand; Melanie A. Zokoll; Franz Zenker Castro; Nina Wardenga; Birger Kollmeier
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.
International Journal of Audiology | 2015
Marc René Schädler; Anna Warzybok; Sabine Hochmuth; Birger Kollmeier
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) 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.
International Journal of Audiology | 2015
Sabine Hochmuth; Birger Kollmeier; Thomas Brand; Tim Jürgens
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.
International Journal of Audiology | 2015
Giuseppina Emma Puglisi; Anna Warzybok; Sabine Hochmuth; Chiara Visentin; Arianna Astolfi; Nicola Prodi; Birger Kollmeier
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.
International Journal of Audiology | 2015
Melanie A. Zokoll; Dilek Fidan; Didem Turkyilmaz; Sabine Hochmuth; İclâl Ergenç; Gonca Sennaroglu; Birger Kollmeier
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.
International Journal of Audiology | 2015
Sabine Hochmuth; Tim Jürgens; Thomas Brand; Birger Kollmeier
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.
conference of the international speech communication association | 2016
Marc René Schädler; David Hülsmeier; Anna Warzybok; Sabine Hochmuth; Birger Kollmeier
In an attempt to predict the outcomes of matrix sentence tests in different languages and various noise conditions for native listeners, the simulation framework for auditory discrimination experiments (FADE) and the extended Speech Intelligibility Index (eSII) is employed. FADE uses an automatic speech recognition system to simulate recognition experiments and reports the highest achievable performance as the outcome, which showed good predictions for the German matrix test in noise. The eSII is based on the short-time analysis of weighted signalto-noise ratios in different frequency bands. In contrast to many other approaches, including the eSII, FADE uses no empirical reference. In this work, the FADE approach is evaluated for predictions of the German, Polish, Russian, and Spanish matrix test in stationary and fluctuating noise conditions. The FADEbased predictions yield a high correlation (Pearsons R = 0.94) with the empirical data and a root-mean-square (RMS) prediction error of 1.9 dB outperforming the eSII-based predictions (R = 0.78, RMS = 4.2 dB). FADE can also predict the data of subgroups with only stationary or only fluctuating noises, while the eSII cannot. The FADE-based predictions seem to generalize over different languages and noise conditions.
International Journal of Audiology | 2018
Hongmei Hu; Xin Xi; Lena L. N. Wong; Sabine Hochmuth; Anna Warzybok; Birger Kollmeier
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.
Journal of the Acoustical Society of America | 2017
Sabine Hochmuth; Tim Jürgens; Thomas Brand; Birger Kollmeier
An objective, language-independent way of predicting observed differences in speech intelligibility in noise across talkers based on their acoustic-phonetic properties was pursued by exploiting speech intelligibility data in stationary speech-shaped noise uttered by bilingual talkers and comparing inter-individual as well as intra-individual speech feature variations across languages. Matrix sentence materials were used that were uttered by bilingual talkers of German/Spanish and of German/Russian and by the respective original matrix test talkers. Various acoustic-phonetic parameters discussed in the literature as being related to speech intelligibility were determined for each talker. Vowel space area, between-vowel category dispersion, and energy in the mid-frequency region represented by the speech intelligibility index were found to be language-independent acoustic-phonetic properties most strongly related to speech intelligibility at least for German, Russian and Spanish. Generally larger inter-indi...