Edward Ozimek

Polish sentence matrix test for speech intelligibility measurement in noise

Abstract 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.

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 S50list for the first set were equal to −6.1 dB and 25.5%/dB, respectively. The mean SRT and the mean list-specific S50list 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 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.

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.

Deformation of frequency modulated (FM) signals propagating in a room

Abstract The paper discusses the analysis of the deformation of frequency modulated (FM) signals propagating in a room. A method used to measure the deformation and a few parameters used to determine frequency and amplitude distortions of a test FM signal are proposed. The results of the experiments reveal that the value of the deformation under investigation depends on the modulating frequency and the deviation range of the FM signal transmitted to the room.

Speech intelligibility tested by the Pediatric Matrix Sentence test in 3-6year old children

Objective: The present study was aimed at the development and application of the Polish Pediatric Matrix Sentence Test (PPMST) for testing speech intelligibility in normal-hearing (NH) and hearing-impaired (HI) children aged 3-6. Methods & Procedures: The test was based on sentences of the subject-verb-object pattern. Pictures illustrating PPMST utterances were prepared and the picture-point (PP) method was used for administering the 1-up/1-down adaptive procedure converging the signal to noise ratio (SNR) to the speech reception threshold (SRT). The correctness of verbal responses (VR), preceding PP responses, was also judged. Outcomes & Results: The normative SRT for the PP method was shown to decrease with age. The guessing rate (@c) turned out to be close to the theoretical value for forced-choice procedures, @c=1/n, where n=6 for the six-alternative PP method (@c~0.166) and n=4 for the four-alternative PP method (@c~0.25). Test optimization resulted in minimizing the lapse rate (@l) (ratio @c/@l~8.0 for n=4 and @c/@l~5.6 for n=6, both for NH and HI children). Significantly higher SRTs were observed for HI children than for the NH group. Conclusions & Implications: For children aged 3-6, tested by the developed PPMST, speech intelligibility performance, for both the VR and PP method, increases with age. For each age group, significantly worse intelligibility was observed for HI children than for NH children. The PPMST combined with the PP method is a reliable tool for pediatric speech intelligibility measurements.

Dichotic perception of modulation depth of AM signals

The aim of this study was to evaluate the resultant value of the modulation depth perceived binaurally when sinusoidally amplitude‐modulated tones, with different modulation depths, were presented to the left and right ear. Different values of the modulation index (ranging from 0% to 100%), modulation frequency (4, 64, 128 Hz), and carrier frequency (250, 1000, 4000 Hz) were used in the experiment. The data show that for low values of the modulation indexes, the dichotic perception of modulation depth approximates the arithmetic mean of the indexes presented to the left and right ear. However, this is not the case for higher values of the modulation index for which the perceived modulation depth is always lower than the mean of the indexes at both ears. Additionally, it was stated that perceived modulation depth does not depend on the rate of modulation for relatively small interaural differences in modulation indexes. In turn, for larger interaural differences the perceived modulation depth tends to decr...

Speech intelligibility determined with various tests presented against noise

The paper describes three Polish tests for assessment of speech intelligibility under noisy conditions: the matrix test, the sentence test and the digit triplet test. The matrix test contains semantically unpredictable sentences of fixed syntactical structures. This test is very useful for long‐term intelligibility measurements and is applicable for subjects with profound hearing loss or cochlear implants users. The sentence test comprises utterances taken from everyday speech and aims at clinical speech intelligibility measurements. The digit triplet test contains sequences of three digits that are spoken separately and is aimed at screening measurements, especially via telephone. The statistical and phonemic properties of the tests are analyzed and compared. The correlation between results obtained in the respective tests and the tests applicability are also discussed.

Dichotic perception of AM and FM signals

The study deals with the binaurally perceived modulation depth (mp) of amplitude‐modulated signals (Exp. I) and binaurally perceived frequency deviation (Δfp) of frequency‐modulated signals (Exp. II), for their diotic and dichotic perception. Various combinations of modulation depth (m) and frequency deviation (Δf) at the left and right ear were used. It was found that when the interaural difference in modulation depth (Δm=ml−mr) or interaural difference in frequency deviation (ΔΔf=Δfl−Δfr) were equal to zero (i.e., diotic perception), the binaurally perceived modulation depth or binaurally perceived frequency deviation were the same as those in monaural perception. For sufficiently small Δm or ΔΔf, the perceived modulation depth, or frequency deviation, approximated the mean of the magnitudes presented to the left and the right ear. However, for large interaural differences in Δm or ΔΔf, the binaurally perceived quantities were lower than their arithmetic means, and showed nonlinear trends. Comparison of...

Detection thresholds of random amplitude modulation

The main objective of this study was to determine the detection thresholds of random amplitude modulation (RAM) as a function of modulation and carrier frequency. Two experiments were performed. Experiment 1 concerned the detection thresholds of AM stimuli for only random amplitude changes at constant modulation frequency. Experiment 2 dealt with detection thresholds for simultaneous, random changes in amplitude and modulation frequency. The data obtained showed that for low modulation frequency, the detection thresholds for sinusoidal amplitude modulation (SAM), random amplitude modulation at constant modulation frequency [RAM(fm const)], and random amplitude and modulation frequency [RAM(fs random)] overlapped one another in the limit of SD. However, for higher carriers and modulation frequencies the RAM(fm const) thresholds were, in a limited range offm , much lower than the SAM ones. When random changes in modulation frequency were combined with random changes in amplitude, the RAM(fm random) threshol...