日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
17 巻, 3 号
選択された号の論文の13件中1~13を表示しています
  • 近野 正, 中村 尚, 杉山 精
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 183-188
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    This paper is the first of a series in which the results of study on the analysis of the transverse vibrating rods analogized with the equivalent electrical network are presented. These vibrating rods are used as an element of the electro-acoustic apparatus or the mechanical filters. First, the transverse vibrating rods are analyzed analogously with the electrical network theory known well; that is to say, the uniform rod having two connecting terminal section is represented with the equivalent network of eight terminals. Based on the above result, the rods of the various end conditions are dealt with. Secondly, the driving point immittance on the rods of the various end conditions are represented with the tables very convenient for practical use. In the next paper the equivalent circuit of the concentrated elements drived with Mittag-Leffler's law will be reported.
  • 中村 尚, 近野 正
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 189-193
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    This paper is the second of a series in which the results of a study on the analysis of the transverse vibrating rods analogized with the equivalent electrical network are presented. The driving point immittance given in the first paper are represented with the equivalent two terminal circuit of the concentrated elements, and the values of the circuit elements are decided with Mittag-Leffler's law and are arranged into tables for plactical use.
  • 佐藤 孝二, 子安 勝, 剱持 富紀夫
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 194-201
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    Usually, the sound transmission properties of wall partitions etc. are characterized by the transmission loss measured in the laboratory. In this case, it is now recommended that the area of test pieces should be at least 10m^2, in order to conform with the practical conditions. However, in the course of fundamental research of sound insulating constructions, it is often desirable to measure the transmission properties conveniently, which may not be necessarily the defined transmission loss. Recently, we have developed a new method suitable for these measurements using small-sized test materials. A small concrete chamber is used for the receiving chamber, which has an opening on upper surface to set the test materials. Interior surface of the chamber is lined with mineral wool absorbers. As the condition of sound source, the following two arrangements are usded: A. The receiving chamber is placed in the reverberation chamber and the reverberant sound is used as the source of sound. B. Absorbent-lined small chamber is placed upon the receiving chamber. Loudspeaker is mounted in this source chamber, directly opposite to the opening of the receiving chamber. Microphone is set in the receiving chamber, and the measurements of transmission are carried out by the following three steps. 1. Without test materials, sound pressure level L_o is measured. 2. After setting the test meterials to the opening, sound pressure level L_c is measured at the same position of microphone. 3. Sound pressure level difference L_o-L_c is calculated, which is used as the measure of transmission characteristics. Position of the microphone is chosen near the sample surface for the source condition A, and apart form sample surface more than 100 mm for the condition B. For single partitions, measured level difference L_o-L_c coincides fairly well with usual transmission loss for the source condition A and with normal incidence mass law for the condition B, at the frequencies higher than the fundamental resonant frequency of the panel.
  • 植村 三良
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 202-206
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    The apparatus analyzes the electrorencephalogram spectrum in the short time interval. The characteristics of this apparatus are as follows: (1)The signal current is recorded into magnetic tape employing the boundary displacement type magnetic recording. The recorded magnetic tape can be developed by mean of spreading iron powder over the tape surface. It is possible to visualize the signal waveform after development and thus, to determine the time interval precisely during which the signal should be analyzed. (2)The selected interval is reproduced repeatedly by a variabl speed rotating magnetic head. By this method, the signal frequency is analyzed over this interval. (3)In the case where the signal is recdrded on paper by electroencephalograph, the necessary part of the recorded signal can be recorded into magnetic tape by use of the pantograph which has a special boundary displacement type magnetic head.
  • 新木 諒三
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 207-212
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    This paper describes the influence of changing similarly the size of magnetic circuit of electromagnetic transducer upon its force factor, inductance of voice coil and negative stiffness , etc. . This principle is helpful not only for the experiment using similar magnetic circuits of different sizes, but also for the design of transducers. Applying this for designing the electromagnetic receiver, we find that the smaller magnetic circuit, or the smaller receiver is the better for increasing specific response, and also that it is preferable that effective mass of armature should not be greater than that of diaphragm.
  • 奥島 基良
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 213-222
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    The author deviced a new tube method for measuring the complex pressure reflection coefficient in water, constructed the apparatus, and measured several samples. This method is a sort of the stationary wave method. In this set up, the bottom surface of a vertical steel tube with thick wall (length 400 mm, inner radius 17. 5mm, wall thickness 6 mm) is driven at one of the longitudinal resonant frequency (about 9, 18, 27 and 36kc)of a Langevin type transducer of barium titanate, and the stationary wave field is formed in the water column between the bottom surface and the sample inserted in the tube from the top. By this method, the principle that the mechanical impedance toward the sample at the bottom takes the minimum or the maximum values, when the sample is moved up and down and as the bottom surface coincides with the node or the loop plane of pressure in the stationary wave field is used. Namely, the amplitude of the complex reflection coefficient is derived from values of these two impedances, which are obtained by measuring the reaction to the transducer surface from the field in the tube, while the phase of the complex reflection coefficient is derived by measuring the distance between the sample and the pressure node plane in which the mechanical impedance takes the minimum value. Two methods, the motional admittance method and the vibrometer method, were devised for the purpose of measuringl the mechanical impedance. The transducer for the vibrometer method has two barium titanate elements for driving and for measuring the velocity amplitude, and it is so designed as to become a multiresonant transducer which vibrates with the same intensity for the most part and is capable of being employed for measuring with equal easiness at four resonant frequencies (9, 17, 27and 36kc). Wooden wedges is generally used for the lining of the unechoic water tank in this country, so the author measured the reflection coefficient of wooden(pine)wedges and plates by this apparatus.
  • 奥島 基良
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 223-229
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    The author a devised method for computing complex acoustic contants of absorbers in water from values of acoustic impedances of the samples which were measured by the set up for measuring complex pressure reflection coefficients. In this method, acoustic constants are computed from measureed values of the acoustic impedance of two samples different in thickness under a condition that back surfaces of samples are kept free, as it is difficult to keep those surfaces rigid in water. This method is capable of being employed even for measuring the constants of samples whose absorption coefficients are zero or very large. Acoustic constants of wood (pine) containing water up to saturation and some trial products of rubbers containning aluminum powder and rubbers containing lead powder as absorbers, were measured at 9〜36kc, and it was found that very likely the absorption coeffisients had close relation to the elasticities. Also, sound velocities in samples of natural rubbers, neoprenes and polyester resins(non-absorbent materials)were measured by this meihod. Differences between measured values by this method at 27kc and those by other methods in higher frquency range, were less than about several percents.
  • 中村 弘道
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 230-243
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
    The carity resonance phenomenon is one of the most important matters that emphasize the interior noise of a car. In order to study this phenomenon, the experiments were carried out by using the two-dimensional model and the acutual car. Moreover, as a method of abating the caving resonance, Helmholtz resonator is employed and its sound absorbing mechanism is examined theoretically and experimentally. As the results, the following are clarified. a)In the car room sound with certain frequency is emphasized and the interior noise is especially enlarged by the cavity resonance. b)The cavity resonance, troublesome as the interior noise occurs in the comparatively low frequency range and is the cause of what is called "closed sound ", and its vibration modes are considered to be (1, 0, 0, ), (2, 0, 0, )and(0, 1, 0). The cavity resonances at high frequency range are out of the question, because absorbing power in the car room is large in high frequency range by the fibrous lining material. c)In the model experiment, as for the cavity resonances in comparatively low frequency range, the reduced frequencies and vibration modes almost coincide with those of the acutual car. That means these phenomena in the acutual car can be inferred from the model experiment. d)Helmholtz resonator would be effective for preventing cavity resonance, if its resonance frequency is designed to coincide with that of cavity resonance. Its effect becomes larger when the volume of th cavity part of the resonator gets larger. e)The sound absorption coefficient of the Helmholtz resonance is the function of its resonator frequency, volume of the cavity part and the quality factor of the resonance in the resonator, as theoretical formula indicates in Ep. (30).
  • 莵原 逸朗
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 244-246
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 松井 英一
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 247-248
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 石井 聖光
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 248-250
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 能本 乙彦
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 250-259
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
  • 佐多 直康, 田淵 大作
    原稿種別: 本文
    1961 年 17 巻 3 号 p. 259-263
    発行日: 1961/09/30
    公開日: 2017/06/02
    ジャーナル フリー
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