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Number of results: 9
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Abstract

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.
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Abstract

The aim of this study was to create a single-language counterpart of the International Speech Test Signal (ISTS) and to compare both with respect to their acoustical characteristics. The development procedure of the Polish Speech Test Signal (PSTS) was analogous to the one of ISTS. The main difference was that instead of multi-lingual recordings, speech recordings of five Polish speakers were used. The recordings were cut into 100–600 ms long segments and composed into one-minute long signal, obeying a set of composition rules, imposed mainly to preserve a natural, speech-like features of the signal. Analyses revealed some differences between ISTS and PSTS. The latter has about twice as high volume of voiceless fragments of speech. PSTS’s sound pressure levels in 1/3-octave bands resemble the shape of the Polish long-term average female speech spectrum, having distinctive maxima at 3–4 and 8–10 kHz which ISTS lacks. As PSTS is representative of Polish language and contains inputs from multiple speakers, it can potentially find an application as a standardized signal used during the procedure of fitting hearing aids for patients that use Polish as their main language.
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Abstract

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.
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Abstract

The impact of musical experience on results concerning sound perception in selected auditory tasks, such as pitch discrimination, pitch-timbre categorization and pitch memorization for blind and visually impaired children and teenagers is discussed. Subjects were divided into three groups: of those with no experience of music, with small musical experience and with substantial musical experience. The blind and visually impaired subjects were investigated, while sighted persons formed reference groups. To date no study has described impact of musical experience on results of such experiments for blind and visually impaired children and teenagers. Our results suggest that blind persons with musical experience may be more sensitive to frequency differences and differences in timbre between two signals as well as may have better short-term auditory memory than blind people with no musical experience. Musical experience of visually impaired persons does not necessary lead to better performance in all conducted auditory tasks.
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Abstract

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.
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Abstract

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-).
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Abstract

Two violins were investigated. The only intentionally introduced difference between them was the type of varnish. One of the instruments was covered with a spirit varnish, the other was oil varnished. Experimental modal analysis was done for unvarnished/varnished violins and a questionnaire inquiry on the instrument’s sound quality was performed. The aim of both examinations was to find differences and similarities between the two instruments in the objective (modal parameters) and subjective domain (subjective evaluation of sound quality). In the modal analysis, three strongly radiating signature modes were taken into account. Varnishing did not change the sequence of mode shapes. Modal frequencies A0 and B(1+) were not changed by oil varnishing compared to the unvarnished condition. For the oil varnished instrument, the frequency of mode B(1+) was lower than that of the same mode of the spirit varnished instrument. Our two violins were not excellent instruments, but before varnishing they were practically identical. However, after varnishing it appeared that the oil-varnished violin was better than the spirit-varnished instrument. Therefore, it can be assumed with a fairly high probability that also in general, the oil-varnished violins sound somewhat better than initially identical spirit-varnished ones.
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Abstract

One-dimensional experimental modal analysis of an unvarnished trapezoidal violin built after the description of F. Savart and an anonymous trapezoidal violin on display in the Music Instrument Museum of Brussels is described. The analysis has revealed ten prominent modes. A mode that may potentially play a role of the “tonal barometer” of the instrument is pointed out. The mode shapes are symmetric and of high amplitude, due to the construction of the instrument. Subjective evaluation of the sound quality demonstrated no pronounced difference between the trapezoidal violin and normal violin.
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