THE JOURNAL OF THE ACOUSTICAL SOCIETY OF JAPAN
Online ISSN : 2432-2040
Print ISSN : 0369-4232
Volume 39, Issue 2
Displaying 1-11 of 11 articles from this issue
  • Yasunobu Nitadori, Tohru Ifukube, Chiyoshi Yoshimoto, Hiroyuki Hattori
    Article type: Article
    1983 Volume 39 Issue 2 Pages 75-81
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    A voice recognition system is proposed for the input device of Japanese word processor, for the voice control of industrial robots and for the communication aids of the disabled. Our device is operated in real time by user's voices which are pronounced as a series of Japanese open monosyllables. The hardware is designed by use of a microprocessor system so that the total system may be a small size and low cost. Input voice is divided into 16 components by 15 channel switched capacitor filters and an envelope detector, and the most suitable area of the consonant part is extracted by investigating the square distance between the input envelope and the reference one. Every extracted pattern is represented by 16x16 dimensional vector after the logarithmic conversion, the level normalizing and the time smoothing. Each input pattern is compared with the reference monosyllabic patterns of a talker by use of the arithmetric processing unit which is developed for the high speed calculation of the square distance between two voice patterns. The time required for the identification of a monosyllable is about 200 msec. From the experimental results by 67x100 monosyllables uttered by 5 speakers, the average rate of correct identifications shows about 96% and the envelope matching method is proved to be effective especially for the identification of the voiced consonants. However, monosyllables following vowel /i/ or /u/ show 2〜4% lowerer correct rate than others and most of confusions occurs between the unvoiced consonants.
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  • Susumu Kitamori
    Article type: Article
    1983 Volume 39 Issue 2 Pages 82-88
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    Interference effects of a trailing tone on recognition for pitch of a brief tonal signal(S_c)presented earlier in time are investigated. In the experiments reported here, all of the experimental conditions are varied randomly, and a same-different procedure is employed. The proportion of correct responses is measured as a function of the silent intertone interval(&Irtri;t)between the S_c and the trailing tone, the trailing tone duration, and the frequency separation between the signal and trailing tone. Furthermore, the temporal growth course of recognition accuracy of S_c are discussed. The d'value of signal detection theory is employed as a measure of the recognition accuracy. The results obtained are as follows:(1)The percent correct recognition for pitch improves with increases in &Irtri;t, but become dull for the long &Irtri;t of about150msec. (2)The interference produced by the trailing tone is independent of its duration. (3)The interference produced by the contralateral trailing tone is as effective as the ipsilateral one. (4)The interference produved by the trailing tone seems to vary with the frequency separation between the signal and tailing tone over200Hz(5)The improvement in the recognition accuracy of S_c can be well fitted with the equation a(t_p)=α{1-exp(-t_p/τ)}, where a(t_p)is the recognition accuracy of S_c, t_p is the presentation time including both the duration of S_c and &Irtri;t, α is a finite asymptote, and τis a time constant.
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  • Yoichi Ando, Kazuhiro Otera, Yuji Hamana
    Article type: Article
    1983 Volume 39 Issue 2 Pages 89-95
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    In this paper, it is confirmed that the most preferred reverberation time is approximately expressed by [T_<sub>]_d &sime;23τ_e(s) where T_<sub> is defined by a decay rate to decrease 60dB after the early discrete reflections and τ_e is the effective duration of the autocorrelation function(ACF) of source signals defined by the delay at which the envelope of normalized ACF becomes just0. 1. Also, it is shown that the most preferred reverberation time is independent of the total amplitude of both early reflections and reverberation relative to that of the direct sound, and is independent of the magnitude of the interaural crosscorrelation(IACC). As is widely accepted, more preferred condition can generally be obtained by minimizing the magnitude of IACC. The maximum values of the crosscorrelation, however, must be maintained at τ=0 to ensure frontal localization of the sound source.
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  • Masao Takeuchi, Atsushi Hiwasa, Hiroshi Shimizu
    Article type: Article
    1983 Volume 39 Issue 2 Pages 96-102
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    A simple method of measuring the phase velocity of surface acoustic waves(SAW's) is proposed. The fundamentals of this method are based on the frequency dependence of radiation angle of an interdigital bulk wave transducer(IDBT) and the incident angle selection in bulk-to-surface mode conversion. The angle beam of bulk waves generated by a sending IDBT impinges onto the surface of a solid passing through a suitable acoustic coupling material and is converted to SAW's on the surface. The SAW's reradiate bulk waves. This signal is detected with a receiving IDBT. The transmission response between the sending and receiving IDBT's indicates a frequency f_0 at which the incident angle of bulk waves coincides with the Rayleigh critical angle. The SAW velocity can be calculated as a product of f_0 and the interdigital period. SAW velocities for various materials are measured by the proposed method. The results of measurements are shown to be in reasonable agreement with the calculated velocities. The method facilitates rapid evaluation of substrate meterials for use in SAW devices.
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  • Osamu Kimura, Kazuomi Itoh
    Article type: Article
    1983 Volume 39 Issue 2 Pages 103-109
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    Production of an ultrasonic equipment with a high output power has been attempted by braze-bonding of ferrite vibrators to it using the active metal method. This paper describes evaluation for the braze-bonding strength of ferrite vibrators by acoustic vibration methods. A composite vibrator is constructed by braze-bonding or by adhering with an epoxy resin of two ferrite vibrators at each surface for acoustic radiation. Each vibrator is driven at the fundamental resonant frequency so that the maximum breaking stress occurs at the jointed surface. On this condition, acoustic duration tests at high vibration amplitudes for a long time and temperature characteristics measurements are carried out for each vibrator. The braze-bonded vibrator is shown to be more than twice as strong as the resinadhered vibrator and thermally more stable for temperature rises up to 120℃. A ferrite vibrator brazed with a metal plate is attached to a water tank and driven at a high vibration amplitude for a long time for an ultrasonic power test into water. The vibrator works stably for 200 hours at the driving power density of 12. 5W/cm^2, which is nearly four times as large as the power rating of commercial ferrite vibrators for single-sided radation into water.
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  • Kohji Motoishi
    Article type: Article
    1983 Volume 39 Issue 2 Pages 110-119
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
    An electrical network model for the generation and distribution of the cochlear microphonic(CM) and the summating potential(SP) is presented and simulated by computer. In the model, inner and outer hair cells are represented by circuits composed of variable resistors, nonlinear resistors, capacitors, and batteries. In addition, branch circuits are connected to the outer hair cell circuits, as the representation of the postsynaptic membranes at the inhibitory synapses. The simulations of the CM and SP as functions of stimulus frequency, intensity, and recording position qualitatively agree well with measurements. Further, the CM and SP are simulated under three different conditions:1. mechanical biasing of the basilar membrane;2. obliteration of the outer hair cells;3. stimulation of the crossed olivo-cochlear bundles(COCB). The responses provide qualitatively good agreement with measurements.
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  • Takao Kawai
    Article type: Article
    1983 Volume 39 Issue 2 Pages 120-
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • Hirokuni Kimura, Kiyofumi Inanaga, Atsushi Matsuda
    Article type: Article
    1983 Volume 39 Issue 2 Pages 121-125
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • Hisao Sakai
    Article type: Article
    1983 Volume 39 Issue 2 Pages 126-129
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • Manabu Ito
    Article type: Article
    1983 Volume 39 Issue 2 Pages 130-138
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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  • Article type: Article
    1983 Volume 39 Issue 2 Pages 139-
    Published: February 01, 1983
    Released on J-STAGE: June 02, 2017
    JOURNAL FREE ACCESS
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