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.

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.

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 (S(50)) 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.

Binaural perception of the modulation depth of AM signals.

The purpose of this study was to determine the binaurally perceived modulation depth (m) of the low rate amplitude modulated (AM) signals, under conditions of their dichotic presentation, i.e., when the AM signals presented to the left and the right ear had different modulation depths. The modulation depth was determined as a point of subjective equality between the sensations of the modulation depth of AM signals presented to the left and right ear, using a one-up, one-down adaptive procedure. Measurements were made for the carrier frequencies (f(c)) of 250, 1000, and 4000Hz, and the modulation frequency (f(m)) of 4Hz. Experimental data showed that, for sufficiently small interaural difference in modulation depth (Deltam), the perceived modulation approximated the mean of the modulation depths presented to the left and the right ear. However, for moderate and large Deltam, the binaurally perceived modulation was lower than the mean of m(l) and m(r) and the steepness of the function m=f(Deltam) gradually decreased with an increase of Deltam. Results of the calculation of the binaurally perceived modulation depth, obtained on the assumption of binaural loudness summation, were found to be consistent within the limit of standard deviation, with the experimental data for relatively wide range of Deltam.