日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
20 巻, 3 号
選択された号の論文の8件中1~8を表示しています
  • 実吉 純一
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 143-
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 梅田 規子, 寺西 立年
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 144-
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 三浦 種敏
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 145-146
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 橋本 富寿, 間庭 愛信, 野田 英邦
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 147-153
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
    In echo sounding of a lake, an artificial lake of an hydroelectric power station, for example, the accurate determination of positions is important. When using an echo sounder installed on a boat it is difficult to determine positions accurately because of shift due to wind or current; and so, the error due to inaccuracy of position is large and great efforts are needed to achieve even approximate accuracy. However, when the lake is frozen, it is easy to determine the positions with accuracy from the surface of the ice and if it were possible to sound from its surface then sounding work would be made much easier. But unfortunately, transmission loss of ultrasonic waves in ice and the existence of air between the ice and the surface of the water had to be taken into account. Hence experiments on sounding from the surface of the ice were made on frozen Lake Haruna in Gumma Prefecture in January and February 1962 and in February 1963. The measured transmission loss in ice of Lake Haruna was 0. 40dB/cm for 200kc and 400kc, and 0. 25dB/cm for 28kc. The echo trace of the bottom was obtained from the surface of ice of the frozen lake by scraping away the snow on the surface with shoes, putting the transducers on it and then pouring over a little amount of water. The sounding was carried out rapidly and accurately. Pond-smelt swimming beneath the ice were also detected from the surface.
  • 山本 照二
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 154-163
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
    The resonance effect in the audible frequency range in small talks studios often results in one of the worst faults known as "coloration". In many cases, this is due to the excitation of the axial mode of vibration with small damping coefficient which exists independently of neighbouring modes. To determine the value of the wall absorption coefficient of small talks studios in order that the coloration of audible low frequency is not perceived, hearing tests were conducted for the just perceptible limit of coloration in terms of Q-values of the relating axial mode and the ratio (D) of the excited level of the mode to that of a mode in the medium or high frequency range. For the tests, four listeners were subjected to speech signals with various degrees of coloration reproduced through a selective amplifier as simulator of transmission characteristics of small talks studios. From the Q-value and the ratio (D) obtained for the just perceptible limit of coloration at 70c/s, 90c/s and 130c/s, it is shown that the absorption coefficient of the wall relating to the axial mode for imperceptible coloration should be larger than 0. 33 for a studio of 6m^3 in volume, and that the absorption coefficient is decreased as the volume is reduced. These values are in good agreement with those hitherto observed in several existing small talks studios of NHK.
  • 近野 正, 中村 尚, 日下部 千春, 富川 義朗
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 164-174
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
    This paper deals with the equivalent electrical network for a transverse vibrating bar under various restricted end conditions. The value of each element of the network is decided so as to be convenient for practical use. Moreover, the authors give electrical networks for the bars whose distributed mass is neglected, and point out a possibility of analyzing easily some simple problems on the "strength of materials" by substituting electrical networks for them. These findings are very useful for the analyses not only of a unit mechanical system but also of composite one combined with unit systems. Further, the graphs showing the frequency characteristics of each element in the impedance or admittance matrices on the bars are appended.
  • 熊本 乙彦
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 175-195
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 中田 和男
    原稿種別: 本文
    1964 年 20 巻 3 号 p. 196-200
    発行日: 1964/05/30
    公開日: 2017/06/02
    ジャーナル フリー
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