日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
26 巻 , 10 号
選択された号の論文の5件中1~5を表示しています
  • 粟屋 潔, 高村 武雄
    原稿種別: 本文
    1970 年 26 巻 10 号 p. 457-469
    発行日: 1970/10/10
    公開日: 2017/06/02
    ジャーナル フリー
    The characteristics, of a special function generator which generates output by convoluting input signals with the internally stored impulse response are calculated and the method of its basic design is given. The function generator of this type may be widely used in future, especially as a speech synthesizer and a model of industrial system for the adaptive control, for it has many advantages:(1) Impulse responses of various types can be easily realized only rewriting the memory, (2) Impulse respone can be changed almost instantaneously, and (3) By changing the time base, the frequency characteristics can be easily varied proportionally. On the other hand the following conditions cannot be avoided practically: (1) The range of integration in the following equation is limited by the finite time duration L, g(t)=∫^^∞__0 f(t-τ)K(τ)dτ (2-1) where g(t), f(t), K(τ) denote the output, input and impulse response respecitvely. (2) The output g(t) is obtained only as a discrete time series. The second condition gives us no problem, if the Lagrange interpolation method is utilized. So the first condition is most essential. The anthors calculated the effect of L and formulas for the integration error, the ratio of peak to dip in frequency characteristics, and of the growth factor at the resonant frequency (see Eqs. (2-8)(2-9), Fig. 2 and Table 1). These equations can be derived by the vector conception shown in Fig. 1, which is a graphical representation of Eqs. (2-7). Furthermore, the authors culcuatred the effects of sampling on the error, and obtained Eq. (2-11) for the ratio of output when f(t) and K(τ) are both discrete to that when f(t), K(τ) are both continuous, Eq. (2-16) for the ratio of output when f(t) is continuous and K(τ) is discrete to that when f(t) and K(τ) are both continuous, and others. When the damping constant α is sufficiently small compared to the angular frequencies ω and β, we have Eq. (2-13) instead of Eq. (2-11) and we may use Fig. 3 and determine the least sampling rate using Eq. (2-15) or (2-17). Therefore the total number (n) of sampling can be determined as the product of L and sampling rate. Concerning the time rate (Δ) of g(t), the authors gave the following formula, <nt(C)>/N≦Δ (5-1) N<<nt(C)>/<t(AD)> (5-2) in which N is the number of parallel operations, t(C) the cycle time of memory, and t(AD) the time necessary for analogue-digital conversion. It is shown from Eqs. (5-1) and (5-2) that the possible high speed operation is limited only by t(AD). All of the formulas mentioned above are summarized in Table 2, which will be conveniently used in the design of the impulse of basic design of speech synthesizer based on the transfer functions of Japanese vowels, given in Table 4. It is seen in Table 3 that the almost satisfactory performances can be obtained from the memory of 0. 5 μsec. cycle time. An electrical circuit which realizes the above mentioned idea, was constructed. Its block diagram and time chart of operation are shown in Fig. 7 and Fig. 8 respectively. Photographs of waveforms of Japanese vowels synthesized by use of this circuit are also shown in Figs. 12〜15.
  • 太田 光雄
    原稿種別: 本文
    1970 年 26 巻 10 号 p. 470-477
    発行日: 1970/10/10
    公開日: 2017/06/02
    ジャーナル フリー
    When a mathematical model of random noise is sought, an important problem is how to unify the deterministic character to describe a time-sequence of random phenomena according to the law of causality and the probabilistic character which accounts for the accidental character existing in actual random phenomena. More concretely, what we must consider are; 1) type of deterministic expression (temporal functions) to be used, 2) kind of probability distribution to be chosen, 3) how to incorporate the probability distribution into the deterministic expression. As mentioned in a previous paper, two models of white noise due to S. O. Rice do not seem to give an organic unity of the deterministic and the probabilistic characters of random noise since the probability distributions are brought into the Fourier series representations at the outset independently of the lapse of time to express a possible variety of amplitude or phase at an arbitrarily fixed time. The truth is that in random processes existing in the physical world all possible varieties of amplitude, phase or other physical quantities really appear in a sufficiently long interval of time. In this paper, we have theoretically introduced a new mathematical model of random noise expressed in terms of uinformly almost periodic functions consisting of arbitrary component waves from the generalized view-point containing the trigonometric series type U. A. P. functions reported in the previous paper. That is, I_N(t)=Σ^^N__<n=1><C_nF(θ_n)>, θ_n&trie;2π(f_nt+φ_n) (mod 2π) with C_n=C_0(∀n), where F(θ) shows an arbitrary single-valued function under the condition of Eq. (2) and all the frequency ratios (such as f_1/f_2/, f_2/f_3, ……) form a set of irrational numbers. Now it is not necessary to introduce any probability distribution law at the outset into the new model, because the probability distribution is automatically formed in the course of time. Thus, a probability density function P(I_N) or cumulative probability distribution Q(I_N) can be expressed in terms of the statistical Hermite series expansion: P(Y)=n(Y){1+Σ^^∞__<n=2>(-1)^nD_n/σ^<2n>H_<2n>(Y)}=n(Y)+Σ^^∞__<n=2>(-1)^nD_n/σ^<2n>n^<(2n)>(Y), Q(Y)=Φ(Y)+Σ^^∞__<n=2>(-1)^nD_n/σ^<2n>n^<(2n-1)>(Y) with a dimensionless variable Y&trie;I_N/σ, as the solution of an intergral equation (16) derived through the calculation of characteristic function g(u) (cf. Eqs. (3) and (10)). Here, n(Y)&trie:exp(-Y^2/2)/√<2π>, Φ(Y)&trie:∫^^Y__<-∞>n(Y)dY and σ^2=NC_0^2/2. It should be noted that P(I_N) is asymptotically normal distribution as N tends to infinity and the choice of F(θ) gives a substantial contribution to the speed of convergence tending to normal distribution. Furthermore, the tables (cf. Tables 1 and 2) of explicit expressions P(Y)(or Q(Y)) in the form of statistical Hermite series expansion are given corresponding to several concrete cases where the component wave F(θ_n) of I_N(t) has respectively the specialized forms. Finally, in a special model of random noise formed in terms of trigonometric series consisting of U. A. P. functions, the characteristic that the nth order moments (n=2, 4, 6, 8, ……) of I_N(t) become asymptotically those of normal distribution (with mean zero and variance σ^2) for large N are discussed.
  • 西宮 元
    原稿種別: 本文
    1970 年 26 巻 10 号 p. 478-487
    発行日: 1970/10/10
    公開日: 2017/06/02
    ジャーナル フリー
    It is well-knowm that reflection sounds of large transit time and high level disturb the audience to listen speech or music. Also, the effect of interference of such reflection sounds given to the speaker cannot be disregarded in our experience. Several studies are performed in this paper about the influence of a single echo given to the speaker, and the following facts are clarified. Tentative criteria for the difficulty in speaking agree with %-disturbance under the conditions that it is in the case of speech, the transit time of single echo is between 50 to 200 msec and the probability of judgment is below 50% (Fig. 3). It can be explained that the effect takes place because the hearing function and the speaking function are formed as a feedback loop in brain and the automatic control action is worked through the feedback loop in the judgment of difficulty in speaking. In other words, the speaker judges "hearing disturbance" in place of "difficulty in speaking" by controling his talker's level and speaking speed. When higher of lower frequency conponents of a single echo are damped down, the criteria for the difficulty in speaking change as shown in Fig. 5, 6, 9 and 10. These problems are illustrated by the collective consideration of temporal masking, remote masking and spectrum distribution of speech. Incidence angle of a single echo to the speaker has no influence on the judgment of difficulty in speaking, excepting for the reflection sound of opposite incidence and small transit time (Fig. 12 and Fig. 13).
  • 騒音研究委員会振動分科会
    原稿種別: 本文
    1970 年 26 巻 10 号 p. 488-494
    発行日: 1970/10/10
    公開日: 2017/06/02
    ジャーナル フリー
  • 騒音測定・評価専門委員会
    原稿種別: 本文
    1970 年 26 巻 10 号 p. 495-497
    発行日: 1970/10/10
    公開日: 2017/06/02
    ジャーナル フリー
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