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Volume 34 , Issue 1
Showing 1-10 articles out of 10 articles from the selected issue
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INVITED REVIEWS
PAPERS
  • Junji Yoshida, Yuta Chaki
    Volume 34 (2013) Issue 1 Pages 19-25
    Released: January 01, 2013
    JOURNALS FREE ACCESS
    In this study, we performed two subjective evaluation tests to obtain factors that affect subjective loudness for environmental noise having a certain duration. In the first experiment, a subjective loudness evaluation was performed using road- and rail-traffic noises having durations of 10 min. As the result, rail-traffic noise was evaluated as being softer than road-traffic noise, although LAeq of the rail-traffic noise was larger than that of road-traffic noise. Rail-traffic noise had longer duration of the low sound pressure level (SPL) and a short, higher SPL peak than road-traffic noise, and we concluded that the factor of the subjective loudness difference depended on the difference in the low SPL frequency. In the second experiment, subjective loudness evaluations were performed using road-traffic noise and modified road-traffic noise. In the modification, the SPL frequency of the road-traffic noise was changed to be similar to that of rail-traffic noise. As the result, the modified road-traffic noise was evaluated as being softer than the original road-traffic noise. In summary, the subjective loudness for a certain length of noise was found to be affected by the frequency of the SPL, and when noise has a long, low SPL duration, it is evaluated as being softer.
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  • Kenji Kurakata, Tazu Mizunami, Kazuma Matsushita
    Volume 34 (2013) Issue 1 Pages 26-33
    Released: January 01, 2013
    JOURNALS FREE ACCESS
    The sensory unpleasantness of high-frequency sounds of 1 kHz and higher was investigated in psychoacoustic experiments in which young listeners with normal hearing participated. Sensory unpleasantness was defined as a perceptual impression of sounds and was differentiated from annoyance, which implies a subjective relation to the sound source. Listeners evaluated the degree of unpleasantness of high-frequency pure tones and narrow-band noise (NBN) by the magnitude estimation method. Estimates were analyzed in terms of the relationship with sharpness and loudness. Results of analyses revealed that the sensory unpleasantness of pure tones was a different auditory impression from sharpness; the unpleasantness was more level dependent but less frequency dependent than sharpness. Furthermore, the unpleasantness increased at a higher rate than loudness did as the sound pressure level (SPL) became higher. Equal-unpleasantness-level contours, which define the combinations of SPL and frequency of tone having the same degree of unpleasantness, were drawn to display the frequency dependence of unpleasantness more clearly. Unpleasantness of NBN was weaker than that of pure tones, although those sounds were expected to have the same loudness as pure tones. These findings can serve as a basis for evaluating the sound quality of machinery noise that includes strong discrete components at high frequencies.
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  • Takeshi Iino, Hirokazu Tatekawa, Hisanobu Mizukawa, Hideo Suzuki
    Volume 34 (2013) Issue 1 Pages 34-41
    Released: January 01, 2013
    JOURNALS FREE ACCESS
    In the three-dimensional (3-D) sound intensity measurement using four-microphone probes, there are two well-known microphone arrangements. One is arranging four microphones at the vertexes of a regular tetrahedron and the other is arranging them at the nearest four corners of a cube. In the high frequency region, these 3-D probes suffer from the same type of sensitivity reductions as do 1-D p-p probes. In this paper, formulae to obtain three orthogonal intensity components for these two types of probes are reviewed first, and their sensitivity and leakage errors are numerically discussed not only for the along-the-axis plane wave incidences but also for incidences from various directions in the 4π space. This analysis reveals characteristic differences of measurement errors of the two types of probes. Since the sensitivity and leakage errors are systematic, it is possible to correct these errors (to some degree) using the source direction information given by a real (or a numerical) measurement. A new correction method is proposed, and the effectiveness of the method is evaluated numerically. Results show that the proposed method is very effective, and the high-end of the frequency range is widened close to the limit, at which the dimension of the 3-D probe is nearly equal to the half wavelength of the incident plane wave.
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REVIEW
  • Kenji Kurakata, Tazu Mizunami, Kazuma Matsushita
    Volume 34 (2013) Issue 1 Pages 42-47
    Released: January 01, 2013
    JOURNALS FREE ACCESS
    ISO 28961, which describes the statistical distribution of hearing thresholds of otologically normal young persons, was established in 2012. The thresholds are those for pure tones of frontal incidence under binaural listening conditions in a free field. Percentiles of the threshold distribution are calculable as a function of frequency from 20 Hz to 16,000 Hz. This international standard is based on the study results of the present authors, who estimated the form of individual distribution using threshold data in their experiments and those in literature adopted in ISO 226 and ISO 389-7. However, because the results were published separately in four journal papers, users of the standard may encounter difficulty in understanding the process of how the threshold data have been integrated and how the threshold distribution has been determined. Therefore, the authors summarize them in this review paper and present an outline of the threshold distribution estimation so that the standard will be understood correctly and used widely.
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