日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
37 巻 , 9 号
選択された号の論文の10件中1~10を表示しています
  • 安藤 繁雄, 山口 公典
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 421-429
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
    This paper describes a method for pitch extraction of musical instrument tones using digital signal processing techniques. The digitized data of musical instrument tones are divided into sequential waves of short-period frames. then Discrete Fourier Transform(DFT) is applied to them. The same operation is successively applied to each frames by one period of the fundamental waveform. The pitch variation Δω_&ltn-1, n&gt is given as a function of time sequences, Δω_&ltn-1, n&gt=(φ_n-φ_&ltn-1&gt)/ΔT. Here, φ_n and φ_&ltn-1&gt are phase of n th and (n-1)th frame, and ΔT is shift time. Using synthesized waveforms, the errors of pitch detection were estimated. The calculated result shows that the good accuracy is obtained for pitch detection except the attack transient part of musical instrument tones which has rapid amplitude variation. Finally, this method is applied to theree natural musical instrument tones, and the results show outstanding feature of pitch variation for the attack transient, the pseudo steady state and the decay part.
  • 久野 和宏, 林 顕效, 池谷 和夫, 三品 善昭
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 430-436
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
    By Using the data obtained from the recent survey of personal noise exposure in daily life, we examined the equivalent sound level Leq during sleep of each subject. Among 210 subjects in and near Nagoya city about 60% of them were in rather good acoustical environments less than 40 dBA during hours of sleep except each transient one hour after going to bed and before getting up. The average Leq of each transient one hour mentioned above was higher by 4 dBA than that of the hours of sleep between them. Although short in duration, 10 minutes or so, about 25% of the subjects were exposed to noise higher than 60 dBA which might disturb their sleep. It was also found that the acoustical environments during sleep are considerably affected by the road traffic and the commercial activities near residence.
  • 太田 光雄, 中村 一正, 生田 顕
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 437-445
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
    In this paper, a new trial for predicting the level probability distribution of road traffic noise fluctuation is considered from a generalized viewpoint in connection with the internal mechanism of noise generation and propagation. More concretely, firstly, the probability distributions on the number of vehicles flowing in an arbitrary road segment is derived on the basis of the probability distributions on an initial phase(introduced by F. A. Haight) and the headway interval which is most fundamental information among many of inside state variables on road traffic flow, from a natural viewpoint of Asychronous Counting method. Next, the noise level distribution at the observation point is theoretically calculated from these information on the flowing state of vehicles, by introducing a new road traffic model based on the compound stochastic process. Furthermore, the legitimacy of the present theory is confirmed experimentally by applying to the traffic noise data actually observed in Hiroshima City.
  • 北守 進
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 446-449
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
    The improvement in the frequency discrimination of a brief tone with the increase in the presentation time is investigated. The frequency difference limens(DL) are measured as a function of the tone duration(D) and the silent interval(Δt) between the two tones. Furthermore, the processing time for the frequency discrimination and the temporal growth course of the perception accuracy of a brief tone are discussed. The results obtained are as follows:(1) In the case where Δt is 0 msec, the DL values monotonically fall with increasing D but approach a finite asymptote for the long D of 150 msec. (2) In the case where D is 10-100 msec, the DL values monotonically fall with increasing Δt but the Δt values requiring to approach a finite asymptote monotonically fall with increasing D. (3) The perceptual processing time needs at least 220 msec for the frequency discrimination of a brief tone. (4) The improvement in the perception accuracy of a brief tone can be well fitted with the equation s(t_p)=α{1-exp(-t_p/τ)}, where s(t_p) is the perception accuracy of a brief tone, t_p is the presentation time including both D and Δt, α is a finite asymptote, and τ is a time constant. The estimated values of α increase with D and that of τ are about 20-30 msec.
  • 西田 正巳, 西山 静男, 柳田 益造, 溝口 理一郎, 角所 収
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 450-451
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 山本 三夫
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 452-457
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 和田 則彦
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 458-461
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 小橋 豊
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 462-465
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 小林 啓美
    原稿種別: 本文
    1981 年 37 巻 9 号 p. 466-471
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 原稿種別: 本文
    1981 年 37 巻 9 号 p. 472-
    発行日: 1981/09/01
    公開日: 2017/06/02
    ジャーナル フリー
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