THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN
Online ISSN : 2432-2040
Print ISSN : 0369-4232
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Volume 37, Issue 6
Displaying 1-7 of 7 articles from this issue
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  • A CRT tuning method on pianos
    Takeshi Yanagisawa, Sadao Suzuki, Masami Ogita, Kijuro Nakamura
    Article type: Article
    1981 Volume 37 Issue 6 Pages 261-266
    Published: June 01, 1981
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.37.6_261
    JOURNAL FREE ACCESS
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    With the synchronous trigger of the reference frequency &fnof;_s Hz suitable to a stretched scale, the observed fundamental wave of the piano sound moves at the rate of the deviation frequency on the CRT screen. The direction of the movement gives that of the pin rotation for tuning and the velocity of movement also does the tuning angle. The result of the pitch deviation with decision time of 0. 2 second represents that the lower limit of a deviation δ (cent) in the bass section is inversely proportional to &fnof;^2_s and the upper limit in the treble section is inversely proportional to &fnof;_s. Therefore;1) In the bass section the CRT tuning method is better used in the frequency range above 110 Hz where the resolution is high and observed with multiples of a detected fundamental wave. 2)In the treble section this method is better applied in the frequency range below 261. 6 Hz where the observable upper limit of deviation is 50 cent, and observed through a frequency divider. Consequently a trial tuning device for practical use is set up and satisfactory results are obtained.
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  • Observations of impulsive shock waves generated by two types of electric discharge in air
    Yoshiaki Watanabe, Takahiko Otani, Yasumasa Urabe, Shigemitsu Yamade
    Article type: Article
    1981 Volume 37 Issue 6 Pages 267-273
    Published: June 01, 1981
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.37.6_267
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    The initial stages of the generation of impulsive sounds caused by two types of electric discharge ; which were the spark discharge and the wire explosion method, were observed by a high-speed photographic recording system combined with the schlieren method. The shapes of the shock front and the propagation velocity near the electrodes were observed using there schlieren photographs. In the sense of sight, it was found that the wave front of impulsive sound generated by the spark discharge using the small gap showed a spherical shape and a sound was generated nearly at the time when the discharge current began to flow. It was also found that the shock fronts produced by the wire explosion method showed the cylindrical shape. The propagation velocity of the shock near the electrodes was measured and the increase of the propagation velocity caused by the highly intensive nonlinearity was recognized. The shock amplitude was estimated by using the observed propagation velocity.
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  • Loudness of fluctuating sound measured by discrimination test
    Hisashi Kado
    Article type: Article
    1981 Volume 37 Issue 6 Pages 274-283
    Published: June 01, 1981
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.37.6_274
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    The stationary sound level is measured as the point of subjective equality (PSE) to the randomly fluctuating sound in loudness discrimination. The fluctuating stimulus is specified with two parameters : fluctuating width and velocity. These are obtained from the distribution curve of the stimulus sound envelope. The stimuli presentation are carried out using stochastic approximation method where the level of the stationary sound is varied sequentially in each test based on the observation of each response. As a result of these tests, a PSE is roughly estimated. The final step is to determine a more accurate PSE through numerical techniques. The results indicate that subjects hear sounds louder as the fluctuation width and velocity are relatively increased. A nonlinear temporal integration model is used to simulate the hearing system. Several frequently occuring levels appear in the model's output (a model of loudness) distribution curve. The average of these levels closely correlates to the calculated PSE.
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  • Measurements of ultrasonic attenuation in seafloor sediments
    Masakatsu Ohgaki
    Article type: Article
    1981 Volume 37 Issue 6 Pages 284-
    Published: June 01, 1981
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.37.6_284
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  • Noise reduction systems
    Takashi Wakuri
    Article type: Article
    1981 Volume 37 Issue 6 Pages 285-289
    Published: June 01, 1981
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.37.6_285
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  • Applications of the generalzed inverse of matrices to acoustic signal processing
    Masuzo Yanagida, Osamu Kakusho
    Article type: Article
    1981 Volume 37 Issue 6 Pages 290-294
    Published: June 01, 1981
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.37.6_290
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  • [title in Japanese]
    Article type: Appendix
    1981 Volume 37 Issue 6 Pages 295-
    Published: June 01, 1981
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.37.6_295
    JOURNAL FREE ACCESS
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