Polish sentence matrix test for speech intelligibility measurement in noise

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 S(50), 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.