THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN
Online ISSN : 2432-2040
Print ISSN : 0369-4232
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Volume 27, Issue 2
Displaying 1-6 of 6 articles from this issue
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  • Oblate Unidirectional Microphone
    Takeo Yamamoto
    Article type: Article
    1971 Volume 27 Issue 2 Pages 71-79
    Published: February 10, 1971
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.27.2_71
    JOURNAL FREE ACCESS
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    This paper shows that a microphone with oblate unidirectional pattern which is semi-circular directional in horizontal plane and hypercardioid directional in vertical plane, can be obtained by combining two directional microphones via a 90-degree phase difference network. In this paper: deviations from the oblate unidirectional pattern caused by differences in sensitivities, directivities, directions of the principal axes of the two microphones, and the angle of the phase-difference network are discussed. Experimental microphones were constructed from a stereophonic coaxial microphone consisting of two varidirectional capacitor microphones. This oblate unidirectional microphone has the semi-circular directional pattern in horizontal plane, 8o that it can be used effectively for a group discussion in television programs. The microphone is less influenced by the reflections from the table as compared with the ordinary unidirectional microphone, because the microphone has small sensitivity in upward and downward directions.
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  • Ultrasonic Attenuation of Transverse Waves in Bonding Layers of Ultrasonic Delay Lines with Piezoelectric Transducers
    Takehiko Uno
    Article type: Article
    1971 Volume 27 Issue 2 Pages 80-86
    Published: February 10, 1971
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.27.2_80
    JOURNAL FREE ACCESS
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    A measurement of ultrasonic attenuation in bonding layer of an ultrasonic delay line is proposed. The method is based on the. fact that the reflection coefficient R and transmission one T of an ultrasonic cave at a bonding layer depend on the attenuation in the layer. Thus, the ultrasonic attenuation in a bonding layer can be determined by measuring R and T. The coefficients of R and T are measured through the use of light diffraction phenomenon due to acoustic waves. The results of the measurement of attenuation constants of transverse waves are reported for several bonding materials.
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  • Electromechanical Coupling Factor of Rectangular Piezoelectric Bimorph Vibrators
    Tatsuo Suzuki
    Article type: Article
    1971 Volume 27 Issue 2 Pages 87-94
    Published: February 10, 1971
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.27.2_87
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    This paper describes theoretical calculations of the electro mechanical coupling factor of the rectangular piezoelectric bimorph vibrator inserted with an elastic plate in several cases. By neglecting the widthward stress as usual, the coupling factor of bending type bimorph was obtained in a simple form, and it was also the same with the twister type bimorph. Exact solution was obtained which takes into consideration the stress in width direction as well as space charge between electrodes and it was compared with the above approximate solution. Further, the coupling factor of the asymmetric type , bimorph was calculated and was compared with that of the symmetric bimorph.
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  • Acoustic-Radiation Pressure on Spheres
    Takahi Hasegawa
    Article type: Article
    1971 Volume 27 Issue 2 Pages 95-104
    Published: February 10, 1971
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.27.2_95
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    The acoustic-radiation pressure due to incident plane progressive wave is computed for isotropic solid spheres, air bubbles and liquid spheres freely suspended in non-viscous fiuids. With respect to solid spheres in water, the elasticity dependency of radiation pressure is investigated using Hasegawa-Yoshioka's theory. It is found that the peaks and minima of the radiation-pressure curve tend to become more pronounced as the density or the sound velocity of material decreases, and that the deviation from the rigid-sphere solution becomes less prominent as poison's ratio decreases for ordinary solids. It is concluded that material such as beryllium is more suitable for ultrasonic-intensity measurement in water than a steel sphere or the like. The acoustic-radiation pressure on fluid spheres is computed using Yoshioka-Kawashima's theory. The radiation-pressure for mercury sphere in water, particularly, shows a series of minima as in the case of solid spheres.
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  • [title in Japanese]
    Article type: Appendix
    1971 Volume 27 Issue 2 Pages 104-
    Published: February 10, 1971
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.27.2_104
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  • Environmental Pollution Caused by the Industries
    Hikaru Shoji
    Article type: Article
    1971 Volume 27 Issue 2 Pages 105-113
    Published: February 10, 1971
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.27.2_105
    JOURNAL FREE ACCESS
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