日本音響学会誌
Online ISSN : 2432-2040
Print ISSN : 0369-4232
28 巻, 5 号
選択された号の論文の8件中1~8を表示しています
  • 実吉 純一
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 223-224
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 桑原 尚夫, 境 久雄
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 225-234
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
    Most of the schemes for recognition of connected speech are based on segmentation of the speech signal into separate units and their subsequent recognition as individual syllables. In view of the face that the acoustical properties of these units are quite different from those of monosyllables uttered in isolation, however, it is to be expected that these units, when taken out from connected speech and presented in isolation, are perceptually different from the corresponding isolated monosyllables. If such perceptual differences are shown to exist, they may serve as improtant evidences for the necessity of incorporating systematic removal of contextual variations into schemes for automatic recognition of connected speech. From this point of view, investigations have been made on the perceptual properties of vowels segmented from isolated monosyllables and connected speech, as well as those of monosyllables and larger units segmented from connected speech, and the following results were obtained: 1. In the case of an isolated C-V syllable, the perception of the consonant was found bo be affrected by the systematic removal of the initial portion of the syllable, unitil finally only the vowel was perceived. The perception of the vowel, however, remained unaffected (Figs. 2 and 3). 2. On the other hand, the perception of a vowel in connected speech was found to be seriously impaired by the removal of its environment. In the case of the vowel/a/, for example, only 12 out of 32 samples in clearly pronounced connected speech received more than 50% correct judgment when taken out from their environments and presented in isolation. The average score of correct identification for the 32 samples was only 57% (Figs. 4 and 5). The scores for the vowels /i/, /e/, /o/ and /u/ ranged from 52% to 70%. These perceptual confusions of vowels in connected speech were found highly correlated with their acoustical properties in the F_1- F_2 plane (Fig. 6). 3. When monosyllabic segments were taken out from connected sppeech and presented in isolation, only 92 out of 219 samples were identified correctly, corresponding to a score as low as 42%. Because of the existence of the preceding consonantal environment, however, the score for the vowels in this case was improved up to about 80%. In the case of bisyllabic segments, the scores of correct identification for the first and the second syllables were 62% and 76% respectively (Fig. 7). In the case of trisyllabic segments, the score for the middle syllable was further improved to 95%, and the score for the middle vowel was as high as 97% (Figs. 8, 9, 10 and 11). These experimental results indicate that the perception of vowels or monosyllables in connected speech is seriously impaired by the complete removal of their environments, and that at least two syllables, one preceding and one following, are necessary to provide a perceptual environment for their correct identification.
  • 北村 音壱, 佐々木 実
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 235-240
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
    Recently, the influence on schools, hospitals and residences by the traffic noise has become a serious social problem with the increase of the amount of traffic on the roads. This report is about an investigation of the estimation method which shows the relationship between physical properties and influences in daily life by traffic noise. A social survey in the vicinity of traffic roads was performed. The following results were obtained. 1) In residences in the vicinity of traffic roads in the daytime, the median of sound level corresponding to "little annoying" is 52 dB(A) and the upper limit of 90% range is 59 dB(A)(Fig. 1), NNI is 45(Fig. 6), NRN is 57(Fig. 8) and Leq is 52 dB(A)(Fig. 9). It is considered that traffic noise should be reduced to less than these values at least in residences in daytime. 2) The NRN value showing that traffic noise in rooms is judged to be quiet is about 30(Fig. 8). This almost agrees with the NRN criterion for conference rooms, reading rooms and bedrooms. 3) The dB(A), NNI, NRN, Leq and SIL can be used for the measurement of influences due to traffic noise, but the relationships between these values and the noise judgement show regression lines with almost equal slope and with the variance of the data. Therefore, it is considered that the out line of the measurement of traffic noise can be observed by only dB(A) median. 4) Influences on daily life due to traffic noise can be estimated by applying the sound levels measured during the five minutes when the traffic volume is large and almost constant, from 10:00 to 16:00 except for 12:003:00, to Figs. 1-5.
  • 高橋 純夫, 森 栄司, 津田 米雄, 金子 誠司, 井出 正男, 大平 悦三
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 241-251
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
    The output power of magnetostrictive transducers and electrostrictive transducers in various ultrasonic power applications will be limited by three major factors. They are (1) Saturation of the driving force, (2) Maximum vibrational amplitude not to cause property degradation due to heat generation or temperature rise and (3) Mechanical fatigue limit of transducer meterials. The values of these factors have to be known for the proper design of vibrating systems that are used in high power applications. In this paper the authors measured the mechanical fatigue limit of the materials of ferrite magnetostrictive transducer and lead zirconate titanate electrostrictive transducer that are practically used today in ultrasonic applications. For the measurement of fatigne limit, we used the Improved Staircase Method that has been developed by I. Yosimoto and used in the field of metals. The Improved Staircase Method is a statistical one that comprises two steps of measurement;usual S-log N curve measurement and staircase measurement. A rough value of fatigue limit obtained from the S-log N curve measurement is used as the initial stress of the staircase measurement. By this procedure a sample mean and a sample standard deviation of the fatigue limit can be obtained. Using these values of the sample mean and the sample standared deviation, it is possible to perform Interval Estimation for the population mean of the fatigue limit. Bar-shaped testpieces made of the same materlials as ferrite magnetostrictive transducer and lead zirconate titanate electrostrictive transducer were provided by four factories. The vibrating system driving the testpiece consists of a ferrite magnetostrictive drive transducer, a metal resonance horn and a vibration pick-up. The testpiece was attached to the thin end of the horn, and set into the longitudinal vibration at 28 kHz resonance frequency. At longitudinal resonance the vibration stress in the testpiece become maximum at the center of its length, therefore fracture is supposed to occur at this position when the testpiece is homogeneous, and the fatigue limit of the material will be represented by the stress S_max at this position. When actually fracture did not occur at the center of the testpiece, only the data about the testpieces that broke within λ/36 from the center of the testpiece were adopted, λ being twice the length, of the testpiece, or the wave length, and the stress S at the position of the fracture was considered to represent the fatigue limit. Stress S within λ/36 from the position of stress maximum is as follows. 0. 985 S_max≦S≦S_max. S_max can be calculated from the density ρ, the sound velocity c of the testpiece and the vibrational velocity υ at the testpiece end which is known by the calibrated output voltage of the vibration pick up. As for metals, stress is to be applied as far as 10^7 cycles. But we increased the number of stress repetitions in the staircase measurement as far as 10^8, considering that the materials were ferrite and ceramics. It can be concluded from the results of the S-log N curve measurements that 10^8 stress cycles are sufficient for the staircase measurement of the fatigue limit. In conclusion, the fatigue limit of the ferrite material was estimated above 3 kg/mm^2. The fatigue limit of the lead zirconate titanate material also turned out to be above 3 kg/mm^2
  • 恒田 有紀, 比企 静雄
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 252-253
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 望月 富雄
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 254-258
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 加川 幸雄
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 259-264
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
  • 若林 駿介
    原稿種別: 本文
    1972 年 28 巻 5 号 p. 265-269
    発行日: 1972/05/01
    公開日: 2017/06/02
    ジャーナル フリー
feedback
Top