THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN
Online ISSN : 2432-2040
Print ISSN : 0369-4232
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Volume 40, Issue 5
Displaying 1-10 of 10 articles from this issue
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  • A general theory of multivariate probability evaluation for arbitrary nonstationary random noise and vibration on the basis of digital level measurement and its application to the actual random noise data
    Mitsuo Ohta, Shizuma Yamaguchi, Kiminobu Nishimura
    Article type: Article
    1984 Volume 40 Issue 5 Pages 293-301
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_293
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    It occurs very often in an actual observation that the ramdom noise and/or vibration are measured in a digital level from at discrete time intervals, since the various statistical evaluations and the extraction of statistical information become easier by use of digital computer. In this paper, firstly, the unified explicit expression of the multivariate joint probability function of discrete level type for an arbitrary non-stationary random noise and/or vibration fluctuation is found in the general form of statistical orthogonal or non-orthogonal expansion series. The joint probability function which can be arbitrarily chosen in advance for convenience of the statistical data analysis is taken into the first term, and the effects of the fluctuation pattern and its non-stationary properties of random phenomena on the joint probability distribution form is concretely reflected in the second and higher order expansion coefficients in the above expansion expression. Next, a trial of the statistical treatment to predict the noise level distribution over long time interval is considered on the basis of information of the noise statistics within a short time interval. Finaly, the effectiveness of the theoretical results are confirmed experimentally by applying it to the actually measured data of non-stationary road traffic noise.
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  • A laboratory study of annoyance due to low level noise in a quiet environment
    Toshie Nakamura, Seiichiro Namba
    Article type: Article
    1984 Volume 40 Issue 5 Pages 302-310
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_302
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    In daily life a person may on occasion find him or herself annoyed by music, speech or the noise of pets, etc. , originating at home or with one's neighbors even though the level of the noise is relatively low as compared with the noise from a factory or an airport. The purpose of the experiments described in this paper is to determine under what conditions these low level noises, e. g. , music, speech, etc. , constitute annoyance. In the first experiment (Exp. 1) the detectability and recognition threshold of three noise sources (i. e. , piano, speech, barking dog) is measured against a broad spectrum background noise of various A-weighted sound pressure levels (25 and 45dB). In experiment 2 the subjects are engaged in a mental task (simple math divition) while exposed to various low level noises and are asked to fill out a questionnaire designed to determine the degree of annoyance the noises posed and whether or not the noises hampered the performance of the task given. It may be concluded that; (a) a source of noise can be identified even though of a lower level than the background noise; (b) even though of relatively low level, a particular noise triggers annoyance in some individuals while having no effect in orders; (c) the degree of annoyance or hinderance of a task does not necessarily correspond to the level of the noise; (d) the degree of annoyance corresponds to the degree of recognition of the noise source; (e) individual responses vary greatly implying the subjective meaning of the noise plays major role in evaluating the annoyance factor of the noise.
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  • On a supporting flange for an ultrasonic stepped solid horn.
    Hiroyuki Shimizu
    Article type: Article
    1984 Volume 40 Issue 5 Pages 311-320
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_311
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    Free vibrations of two typical stepped solid horns are analyzed two-dimensionally and axisymmetrically by means of the finite element method. The result analyzed shows clearly the influence of a stepped shape on vibrational properties of the horn, and shows the fact that a vibration node does not exist on surface of the horn. Then, a problem arisen is how to find out an optimum support position of the horn and an optimum geometry of a supporting flange. The problem is investigated experimentally. A vibration system consisting of a vibrator, horn and supporing flange is constructed, and its mechanical and electrical characteristics are measured. From the results measured, the optimum conditions for the supporting flange for the horn are examined, and a design procedure of the supporting flange is obtained.
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  • Effects of plate thickness upon sound radiation from vibrating beams without baffle
    Setsuo Maeda, Yasufumi Kume, Fumio Hashimoto
    Article type: Article
    1984 Volume 40 Issue 5 Pages 321-326
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_321
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    In this paper, the effect of plate thickness upon the sound radiation from the vibrating free-free beams without baffle is investigated. The relation between the acceleration amplitude and the radiated sound pressure of unbaffled beams is theoretically analyzed. In this analysis, the mechanism of sound radiation from a vibrating beam without baffle is assumed to be equivalent to that from two pulsating spheres in arraying to longitudinal direction that have a phase difference of 180゜and the same amplitude as the beam surface. The analytic results are verified by experiments. As a result of many considerations, the effects of the plate thickness upon sound radiation from vibrating unbaffled beams are cleared. When the results of this analysis are applied to the damping treatment beams, an agreement between the experimental results and the numerical results is obtained.
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  • Optimally phase-fluctuation tolerant waveforms for a system using correlation detection
    Eiichi Kashiwagi
    Article type: Article
    1984 Volume 40 Issue 5 Pages 327-331
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_327
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    This paper attempts to find optimally phase-fluctuation tolerant waveforms, i. e. , signals such that magnitude of correlator output is relatively insensitive for phase-fluctuation. A correlation process is used by reason of producing a sufficient statistic effect for the detection of an echo in Gaussian noise. But a degradation of correlator output is caused by phase-fluctuation. So, to derive the signal minimizing the degradation, an analysis is made by using techniques of variational calculus, with appropriate constraint condition for making physically realizable waveforms. The derived signal represents such a property that its frequency changes to be inversely proportional to the second power of its envelope, i. e. , that the lower frequency is distributed to get the higher power and vice versa, under the energy and center frequency constraints. This result gives the theoretical derivation for the property that the smaller degradation of the detection is brought as the signal frequency becomes lower, which is qualitatively well understood.
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  • Discrimination of Japanese voiceless stop consonants by burst spectrum.
    Shigeyoshi Kitazawa, Shuji Doshita
    Article type: Article
    1984 Volume 40 Issue 5 Pages 332-339
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_332
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    We determined the extent to which the burst spectrum of Japanese p, t, k could be correctly classified by a set of vowel and speaker independent linear discriminant functions. The stops were produced in the context of CV utterances by 28 male speakers. Following the invariance hypothesis of gross shape of burst spectrum, the normalized power spectrum was computed from the visually extracted burst portion by the autocorrelation method of linear prediction analysis. The spectrum was represented with 28-dimensional components corresponding nearly to critical bandwidth filter outputs up to 9. 25 kHz. Quadratic transformation of some pairs of components was useful for classification. Using rather small number of components selected by stepwise process, the linear functions discriminated consonants correctly more than 80%, and about 90% if the target vowel was known.
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  • Characteristics and analyses of shear mode piezoelectric ceramic transducer for Rayleigh and longitudinal waves
    Yoshiro Tomikawa, Hiroaki Yamada, Morio Onoe
    Article type: Article
    1984 Volume 40 Issue 5 Pages 340-348
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_340
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    This paper deals with characteristics and analyses of an ultrasonic transducer using shear mode piezoelectric ceramics in order to develop a new transducer for Rayleigh and longitudinal waves attached importance to detection of acoustic emission and non-destructive inspection. The transducer using shear mode shows some inherent characteristics which the normal transducer of longitudical mode does not have. Untill now, however, it is not investigated enough yet how its inherent characteristics are related to the vibrational behaviors of shear mode piezoelectric ceramics. In this paper, the characteristics of shear mode piezoelectric transducer are investigated experimentally and analytically. In the first part, the characteristics for radiation and detection of Rayleigh wave are presented and the behaviors are analyzed by finite element method. From informations it is found why the shear mode transducer can radiate and detect Rayleigh wave through oil layer matching the transducer to soft steel mediam. The second part constains characteristics for radiation of longitudinal wave ; it is proved that possibility of longitudinal wave radiation can be drawn from the results of analyzed behaviors and it is ascertained by experimentally. Moreover the direction of radiated longitudinal wave is also analyzed by a simple acoustic model. The third discusses characteristics of a tapered shear mode piezoelectric transducer. This transducer is to use multi-resonance modes caused by tapered construction and is for purpose of a wide frequency band characteristic. Finite element analysis of this transducer is also done and its mode pattern for frequency is shown.
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  • Self-demodulation of a plane acoustic wave : Study on primary wave modulation for wideband signal transmission
    Shigeaki Aoki, Tomoo Kamakura, Kazuo Ikegaya
    Article type: Article
    1984 Volume 40 Issue 5 Pages 349-356
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_349
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    Broad-band parametric signal generated by the self-demondulation effect of amplitude-modulated wave in an acoustic tube has been discussed in this paper. First, the fundamental nature of transient parametric signal by a large amplitude pulse has been given. The theory presented here has been basically dependent on the Merklinger's description [J. Acoust. Soc. Am. 58, 784-787 (1975)]. Although the theory excludes wall effect of the tube, it satisfactorily agrees to the experimental data. Next, the problem of transmitting a continuous broad-band signal is treated. For the modulation of primary wave, a new type of modulation, that is, squarely rooted amplitude-modulation has been proposed, and it has been concluded that harmonic distortions of reproduced signal are less than those by double- and single-sideband waves.
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  • Report of Ultrasonics International 1983
    Jiromaru Tsujino
    Article type: Article
    1984 Volume 40 Issue 5 Pages 357-358
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_357
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  • New IEEE SU Society Tokyo Chapter and Report on 1983 IEEE Ultrasonic Symposium.
    Yasutaka Shimizu
    Article type: Article
    1984 Volume 40 Issue 5 Pages 359-362
    Published: May 01, 1984
    Released on J-STAGE: June 02, 2017
    DOIhttps://doi.org/10.20697/jasj.40.5_359
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