日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
27 巻 , 12 号
選択された号の論文の9件中1~9を表示しています
  • 山口 公典
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 601-610
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
    Here, two experiments were carried out on the attack transient of pure tones, with special regard to the differences in tone quality of natural musical instruments and an electronic musical instrument. Recently, several researchers have pointed out that the attack transients of overtones are important physical factors affecting the tone quality of musical instruments. In this paper, we report mainly the result of the first experiment and the mathematical classification of the attack transient patterns. In the first section, the differential limen of the attack time (T) of pure tones was experimentally measured. The frequency of pure tones was set at 100, 400 and 1, 000 Hz. The factorial design of auditory experiments is shown in Table 1. The results, in Fig. 2 indicate that the differential limen decreases when the frequency becomes higher. The ratio of ΔT/T, being about 0. 35 in 100 Hz and about 0. 26 in 1 kHz. The decay time and the duration of pure tones only affected the differential limen a little. In the second section, 500 patterns of various attack transients for pure tones were classified mathematically by the linear discriminant technique. First, both the time and intensity of the transients were quantized into 15 steps, as the model in Fig. 3 shows. Here, the maximum length of the attack duration was set to 300 msec, which was divided into 15 equal appearing parts, consulting the value of differential limen obtained in the first experiment. Next, with linear discriminant function, a classification of these attack transient patterns was attempted. Fig. 4 shows the distribution of inner products obtained in the analysis. With this analysis, the 500 patterns were finally classified into 34 clusters. The results of experimental examination on the auditory characteristics of 34 clusters are described in the next paper.
  • 山中 晤郎, 安達 勤
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 611-618
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー

    It was found that there were two frequency groups of acoustic disturbances which gave much influence upon vortex-shedding from a circular cylinder in an air flow. One has a narrow frequency range centering on the natural vortex-shedding frequency f_n, the other has a relatively wide frequency range which corresponds with the frequency of the laminar-turbulent transition wave f_t in the separated boundary layer from the cylinder surface, i. e. , in the shear layer. In order to investigate the growth of the periodic velocity fluctuations, auto- and cross-correlation functions for the maximum velocity fluctuation (u)_<max> in the shear layer were analyzed with the aid of DISA hot-wire anemometers (model 55D01), a TEAC real-time digital correlator (model C-110) and so on. Fig 1 gives the block diagram used to obtain the cross-correlation function R_<12>(τ) defined by eq. (2). In our experiments, the datum probe in Fig. 1 was fixed at the position where two of the different frequencies of the periodic velocity fluctuations in f_n and f_t were observed simultaneously. We got the optimum delay time τ_0 from R_<12>(τ) to investigate the travelling of the periodic velocity fluctuations. The detail of the experimental apparatus is described in reference 1). Fig. 2-1 gives the auto-correlation coefficients R_<11>(τ)/(R_<11(0)>) for (u)_<max> in the natural shear layer (Re≒1800, U_∞≒3. 4 m/s, f_n≒85 Hz). In the laminar region of the shear layer close to the cylinder there was no periodicity in the velocity fluctuations. But, at x/d=1. 327, a sinusoidal velocity fluctuation by the transition wave was detected in the random velocity fluctuation, and it's amplitude grew downstream. The frequency of the transition wave was about 250 Hz. It was found from the cross-correlations (Fig. 3-1) that this wave propagated in the direction of the air flow with a velocity of about 0. 74U_∞ in the region 0. 8<x/d<2. 1. Further downstream, the correlation for the periodic turbulence originated from vortex-shedding was superior to that for the transition wave. On the other hand, the influence of acoustic disturbances upon the laminar region of the shear layer (Fig. 5). In this paper, two progressive sound fields with the frequency f_a=85 Hz (≒f_n) and 246 Hz (≒f_t) were superimposed upon the flow field. The intensity of the acoustic particle velocity in y-direction v_<fa>/U_∞ (U_∞≒3. 4 m/s) were about 0. 3% at the cylinder position in both sound fields. When the acoustic disturbance with f_a=246 Hz (≒f_t) was superimposed upon the flow field, even near the cylinder (at x/d=0. 449), the transition wave could be detected by auto-correlation measurements (Fig. 2-3), and propagated downstream in the region 0. 5<x/d<1. 8 by cross-correlation measurements (Fig. 3-3). This region was nearer to the cylinder than the natural one. Then, laminar-turbulent transition in the shear layer was promoted by the superimposition of this acoustic disturbance. But, the wave also had the velocity of about 0. 74U_∞, and this velocity was not influenced by the acoustic disturbance superimposed upon the flow field. When the acoustic disturbance with f_a=85 Hz (≒f_n) was superimposed, (u)_<max> in the shear layer behaved in an almost sinusoidal fluctuation in the vortex-shedding frequency throughout the whole shear layer (Fig. 2-2). The transition wave was not detected in the shear layer (Fig. 2-2). It is shown in Fig. 3-2 that throughout the laminar region of the shear layer, i. e. , x/d<(x/d)_t, optimum delay time τ_0/T was nearly 0. 5, where T was the period of vortex-shedding. In other words, velocity fluctuations in the vortex-shedding frequency between upper and lower shear layers are in adverse phase. Further downstream, in the region x/d>(x/d)_t, τ_0/T increased with increasing x/d, and in x/d>3. 5, vortices formed from the shear layer travel in the

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  • 津村 尚志, 千葉 滋, 曽根 敏夫, 二村 忠元
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 619-629
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
    Investigations into frequency analysis in the ear have been made from various points of view, and reports by many researchers show that the ear exhibits different characteristics according to the conditions of stimulus presentation because of the neural complexity. Almost all of the sounds which we experience in everyday life suffer changes in contents, for instances, durations of vowels and consonants are usually less than 100 msec, and also in musical sounds a steady state does not even continue for a second. To know the auditory response to such a sound, therefore, it is necessary to study the temporal process of frequency analysis in the ear. In this article we discuss by means of temporal masking how the auditory excitation pattern along the frequency axis is developed when a tone burst or a short tone containing two frequency components is presented, and further consider the time required for frequency analysis in the ear on the basis of detection threhelds of frequency transition of sounds with the initial steady segment and the final one. When a signal tone (with duration of 30 msec) is given close on the heels of a masker (tone burst of a frequency of 1, 000 Hz), the difference between the threshold shift at 1, 000 Hz and ones at other frequencies (1050 and 1100 Hz) is nearly zero for masker's duration of 10 msec, and increases as duration of the masker is lengthened to attain a stationary value at about 100 msec (Fig. 2). Investigating into the wider frequency range of signal sound, the masking curves (masking audiograms) are obtained as shown in Fig. 3 (a) and (b). No peak aspears on the masking curve for masker's duration of 10 msec. This is considered to show the imperfection of lateral inhibition in the neural network. It must be noted that the threshold shift at 1, 000 Hz for the masker's intensity of 95 dB SPL (Fig. 3-a) is a little different from that for the intensity of 80 dB SPL (Fig. 2), when the duration of masker is 10 msec. For masker's duration of 25 msec, a peak is clearly observed at 1, 000 Hz. When a complex tone with two components (with frequencies of 800 and 1, 000 Hz) is given as a masker, a duration of more than 25 msec is required for the appearance of the peaks at frequencies of the components (Fig. 4). Frequency width (-3dB band width) of the aural response to a single frequency tone (with a frequency of 1, 000 Hz) calculated from the above results decreases along with an increase of duration of the tone, and finally attains the constant value of about 15 Hz at the duration of 100〜300 msec. This result means that the band width of the auditory filter changes as a function of time, and it is translated into a change of its sharpness in Fig. 13. When the frequency of a tone burst is linearly changed from the initial frequency of 1, 000 Hz during a portion of the burst, detection thresholds of rapid frequency transition expressed in the frequency difference between its initial frequency and the final one depend on the duration of a steady part before and after the transition, and attain a constant value for the steady duration of 100〜300 msec (Fig. 9 and Fig. 11). For the shorter transition duration (5 msec), the relation between the duration of a steady part before the transition and the detection threshold corresponds approximately to the relation between duration of tone burst and the one-fifth frequency-bandwidth of aural response (Fig. 12). When the duration of a steady part is short, the detection threshold of frequency transition is affected by the transition duration a lot and the longer the transition duration, the easier it is to detect the transition. This range may require consideration from other angles such as the behavior of neurons sensible to frequency modulated tone.
  • 原稿種別: 付録等
    1971 年 27 巻 12 号 p. 629-
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
  • 市川 熹, 中田 和男
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 630-631
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
  • 斉藤 清, 青木 由直
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 632-633
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
  • 藤崎 博也, 小畑 幸枝, 田崎 良三
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 633-635
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
  • 吉村 正蔵
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 636-642
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
  • 持田 康典, 日吉 昭夫
    原稿種別: 本文
    1971 年 27 巻 12 号 p. 643-648
    発行日: 1971/12/10
    公開日: 2017/06/02
    ジャーナル フリー
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