THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN
Online ISSN : 2432-2040
Print ISSN : 0369-4232
Volume 39, Issue 6
Displaying 1-10 of 10 articles from this issue
  • [in Japanese]
    Article type: Article
    1983 Volume 39 Issue 6 Pages 359-360
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • Mitsuo Ohta, Shizuma Yamaguchi, Yasuo Mitani
    Article type: Article
    1983 Volume 39 Issue 6 Pages 361-366
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    It is obvious that a strictly stationary random process seldom exists in the practical random phenomena such as urban noise and vibration. In the actual observation of random noise and Vibration environment, it occurs very often that the level data of random noise and vibration are sampled in the digital form at discrete time intervals by use of a sound level meter and vibration meter. Hereupon, the use of digital computer is essential for various types of statistical evaluation(e. g. , median, mean value, variance, L_x, etc. )on the above random noise and vibration data. From these practical points of view, a unified expression of random noise and vibration level distribution which is applicable to arbitrary types of distribution form and nonstationary characteristics is newly established in this paper. More concretely, the explicit expression of probability function for randam noise and vibration level fluctuation is derived in the general form of statistical orthogonal expansion series. Next, based on the above unified expression, a new algorithm estimating the representative statistics such as L_x level is theoretically proposed, in the sequential form of on-line treatment. Finally, the actual effectiveness of the proposed on-line estimation method is experimentally confirmed by applying it to the experimentally observed road traffic noise data in the city.
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  • Yoichi Nakazono
    Article type: Article
    1983 Volume 39 Issue 6 Pages 367-373
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    The distribution of noise source strengths in a coaxial double jet with main nozzle diameter 12mm and nozzle exit area ratio 2. 83of bypass flow to main flow is measured by the use of a reflector-type directional microphone system. Sound pressure spectrum in the far-field which is predicted with the sound source distribution is in well agreement with the measurement by an omnidirectional microphone at each velocity ratio of the bypass jet to the core jet. Therefore, a reflector type directional microphone system is considered to be suited for the measurement of sound source distribution in the coaxial double jet. Next, the author measures the pressure fluctuation in an incompressible jet flow with the use of a probe microphone with four static pressure holes and obtains the influence of correlation upon the far-field noise at each Strouhal number on the basis of the distribution of noise source strength and local pressure fluctuation. Moreover, the reason of the noise increase or decrease of the double jet to the single jet is considered.
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  • Takao Kawai
    Article type: Article
    1983 Volume 39 Issue 6 Pages 374-379
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    An asymptotic solution of the scalar wave field due to a point source above a locally reacting plane surface is derived by the modified saddle-point technique and approximation of the surface wave term. The solution has a similar simple form to the Lawhead-Rudnick solution and the Ingard solution, and gives the perfectly uniform continuous field above the boundary. Numerical calculation indicates that the solution is more accurate than the Lawhead-Rudnick solution and the Ingard solution
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  • Hiroyuki Yamane, Youichi Ito, Masatada Kawamura
    Article type: Article
    1983 Volume 39 Issue 6 Pages 380-387
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    In this paper, the angle dependence of radiated sound pressure and radiation ratio are investigated in the frequency range of λ/λ_p&lt1 for the rectangular plates which vibrate in the stripes mode. They are calculated with introducing an angle component of the volume velocity at an elementary area on these plates whose angle component is determined by an angle between the rectangular plate and the plane containing the center axis parallel to the stripes and the observation point. The sound radiation from a surface of these plates is considered to be the radiation of sound from the bending waves in the plates which are propagated perpendicular to the stripes for the positive and negative directions. The radiation of sound from the bending wave in the one direction is approximated by the sound radiation from the rectangular piston which vibrates the maximum value of vibrational velocity of the bending waves, the dimensions of the rectangular piston are the same length of the parallel side to the stripes in width and √ &lt1-(λ/λ_p)^2&gt times the original side of the plates in length. The radiation ratio of these plates is expressed as √ &lt1-(λ/λ_p)^2&gt. The experimental results are in good agreement with the calculated ones.
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  • Kenjo Yamakoshi
    Article type: Article
    1983 Volume 39 Issue 6 Pages 388-
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
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  • Haruko Kawasaki
    Article type: Article
    1983 Volume 39 Issue 6 Pages 389-397
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • Keiji Yanagisawa
    Article type: Article
    1983 Volume 39 Issue 6 Pages 398-404
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • Takeshi Itow
    Article type: Article
    1983 Volume 39 Issue 6 Pages 405-413
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • [in Japanese], [in Japanese], [in Japanese]
    Article type: Article
    1983 Volume 39 Issue 6 Pages 414-423
    Published: June 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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