(2015). The multilingual matrix test: Principles, applications, and comparison across languages: A review. International Journal of Audiology: Vol. 54, Overcoming Language Barriers: Matrix Sentence Tests With Closed Speech Corpora, pp. 3-16. doi: 10.3109/14992027.2015.1020971

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.

The purpose of this study was to develop the Polish sentence matrix test (PSMT) to measure intelligibility of speech presented against a background noise. The PSMT consists of five columns containing: 10 names, 10 verbs, 10 numerals, 10 adjectives, and 10 nouns. Since each word was available as a separate sound file, it was possible to generate different sentences by juxtaposing randomly selected words taken from respective columns. This approach allows 100 000 unique sentences of a fixed grammatical structure to be generated. The speech reception threshold (SRT), i.e. the signal-to-noise ratio (SNR) providing 50% speech intelligibility and S₅₀, the slope of an intelligibility function at the SRT point, were shown to be −9.6 dB and 17.1 %/dB, respectively. Note that in this study dB is regarded as dB SNR, otherwise reference is given. PSMT was also evaluated using an adaptive 1-up/ 1-down staircase procedure in investigations with and without participation of an experimenter. No significant differences were shown for SRTs obtained in these investigations. Sumario El propósito de este estudio fue desarrollar la prueba matriz de frases en polaco (PSMT) para medir la inteligibilidad de lenguaje presentado contra ruido de fondo. El PSMT consiste de cinco columnas que contienen: 10 nombres, 10 verbos, 10 numerales, 10 adjetivos y 10 palabras. Dado que cada palabra estaba disponible como un archivo de sonido separado, fue posible generar diferentes frases por medio de la yuxtaposición aleatoria de palabras seleccionadas tomadas de las respectivas columnas. Este enfoque permite la generación de 100.000 frases singulares con una estructura gramatical fija. El umbral de recepción del lenguaje (SRT), p.e., la tasa de señal-ruido (SNR) brindando el 50% de inteligibilidad del lenguaje, y el S50, la pendiente de una función de inteligibilidad en el punto del SRT, fueron –9.6 dB y 17.1%/dB, respectivamente. Note que en este estudio los dB corresponden a dB SNR, a menos que se brinde otra referencia. También se evaluó el PSMT usando un procedimiento adaptativo en escalera de 1 hacia arriba y 1 hacia abajo, en investigaciones con y sin un experimentador. No se encontraron diferencias significativas para los SRT obtenidos en estas investigaciones.

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.

Purpose: New complementary multilingual speech-in-noise tests in Russian, Turkish, and Spanish for hearing self-screening purposes and follow-up hearing diagnostics are compared to the speech tests of the European project, HearCom (Hearing in the Communication Society). Method: The tests consist of spoken numbers (Digit Triplet Test; Smits, Kapteyn, & Houtgast, 2004) or sentences (Matrix Test; e.g., Hagerman, 1982) presented in a background noise and estimate the speech reception threshold, which is the signal-to-noise ratio that yields 50% speech intelligibility. All tests were developed according to the HearCom minimum quality standards for speech intelligibility tests. This report presents a cross-language comparison of reference speech intelligibility functions for monaural headphone measurements with normal-hearing listeners. The same model function was employed to describe the speech intelligibility functions for all of the tests. Results: Reference speech intelligibility functions of the new versions of the Digit Triplet Test and Matrix Test show high comparability to the HearCom tests. In order to achieve the highest possible comparability across languages, language- and speaker-dependent factors in speech intelligibility should be compensated for. Conclusion: To date, several complementary tests for screening and diagnostics have been developed in several languages. Adhering to the HearCom standards, the tests are highly comparable across languages. For the Matrix Test, equal syntax and linguistic complexity were maintained across languages due to common methodological standards.

In order to study the interaction between the intelligibility advantage in rooms due to the presence of early reflections and due to binaural unmasking, a series of speech reception threshold experiments was performed employing a single reflection of the frontal target speech source as a function of its delay ranging from 0 to 200 ms. The direction of the reflection and the spatial characteristic of the interfering noise (diotic, diffuse, or laterally localized) were varied in the experiments. For the frontal reflection, full temporal integration was observed for all three noise types up to a delay of at least 25 ms followed by gradual intelligibility decay at longer delays. At 200 ms delay the reflection introduced additional intelligibility deterioration. For short delays, intelligibility was not reduced when the reflection was spatially separated from the direct sound in the diffuse and lateral noise conditions. A release from the deterioration effect at 200 ms delay was found for all spatially separated reflections. The suppression of a detrimental reflection was symmetrical in diffuse noise, but azimuth-dependent in lateral noise. This indicates an interaction of spatial and temporal processing of speech reflections which challenges existing binaural speech intelligibility models.