The aim of the study was to determine the signal-to-noise ratio (SNR) for the Speech Reception Threshold (SRT) for young persons with normal hearing. The following three tests available for Polish language were used: the New Articulation Lists (NAL-93) version of 2011, the Polish Sentence Test (PST) and the Polish Sentence Matrix Test (PSMT). When using PST and PSMT the masking signal was babble noise made of the language material contained in the test. For NAL-93 the masking signal was speech noise. The speech reception threshold (SRT) was found to be (−6:8 ± 1.1), (−4:8 ± 1.6), (−3:5 ± 1.8) and (−3:4 ± 2.0) dB SNR for PST, PSMT, NAL-93 (constant stimuli method) and NAL-93 (short method), respectively. The values of SRT depend on semantic redundancy of the language material. Differences in SRT were statistically non-significant only for NAL-93 (constant stimuli method) and NAL-93 (short method). Moreover, it was shown that the time needed for presentation of a single word list (NAL-93, short method) or single sentence list (PST, PSMT) was comparable and equal to 2–3 minutes. The most uniform SRT values were obtained for PST. The PSMT was the least demanding for the listener, experimenter and equipment.
The main goal of the research was to obtain a set of data for ability of speech in noise recognition using Polish word test (New Articulation Lists – NAL-93) with two different masking signals. The attempt was also made to standardise the background noise for Polish speech tests by creating babble noise for NAL-93. Two types of background noise were used for Polish word test – the babble noise and the speech noise. The short method was chosen in the study as it provided similar results to constant stimuli method using less word material. The experiment using both maskers was presented to 10 listeners with normal hearing.
The mean SRT values for NAL-93 were −3.4 dB SNR for speech noise and 3.0 dB SNR for babble noise. In this regard, babble noise provided more efficient results. However, the SRT parameter for speech noise was more similar to values obtained for other Polish speech tests. The measurement of speech recognition using Polish word test is possible for both types of masking signals presented in the study. The decision as to which type of noise would be better in practice of hearing aid prosthetics remains an open-end question.
The present work discusses results concerning sound perception obtained in a pitch memorization experiment for blind and visually impaired subjects (children and teenagers). Listeners were divided into two age groups: 7-13 year olds and 14-18 year olds. The study tested 20 individuals (8 congenitally blind and 12 visually impaired) and 20 sighted persons comprising reference groups. The duration of the experiments was as short as possible due to the fact that our listeners were children. To date, no study has described results of such experiment for blind/visually handicapped children and teenagers. In the pitch memory experiment blind teenagers outperformed blind children and both age groups of visually impaired subjects in two out of three tested cases. These results may have implications for the development of auditory training in orientation and mobility of young visually handicapped people.
Experimental modal analysis of a violin with three different tensions of a bass bar has been performed. The bass bar tension is the only intentionally introduced modification of the instrument. The aim of the study was to find differences and similarities between top plate modal parameters determined by a bass bar perfectly fitting the shape of the top plate, the bass bar with a tension usually applied by luthiers (normal), and the tension higher than the normal value. In the modal analysis four signature modes are taken into account. Bass bar tension does not change the sequence of mode shapes. Changes in modal damping are insignificant. An increase in bass bar tension causes an increase in modal frequencies A0 and B(1+) and does not change the frequencies of modes CBR and B(1-).
It has been shown in the present paper that exploitation of the experimental potential of a photoacoustic technique can provide information on a type of intermolecular interactions in aqueous mixtures containing organic liquids, when the basic parameters of these mixtures, such as density, ρ, specific heat, cp, or thermal conductivity, λ, are unknown. Earlier investigations of concentration dependence of effusivity in different aqueous solutions of organic liquids demonstrated that the photoacoustics method is a sensitive tool to identify hydrophobic properties of such liquids. In our experiment this suggestion was exploited for a solution of methanol which is known to display much weaker hydrophobicity than other alcohols.
It was confirmed that the location of extreme deviations from linearity for the thermal effusivity, Δe, agrees well with that of characteristic points for the isentropic compressibility coefficient, κS, and the excess molar volume, V_m^E, as a function of the concentration.