To study voice source characteristics in speech, it is essential to record vocal cord vibration simultaneously with the speech signal and to analyze the relationship between the pattern of the vocal cord vibration and the acoustic characteristics of the speech signal. For the purpose of observing vocal cord vibration during running speech, a special high-speed digital image recording system using a flexible fiberoptic endoscope was developed. In the present paper, the general features of the system are described, together with some preliminary results of an analysis of vocal cord vibration in the production of Japanese consonants. Characteristic differences in the pattern of vocal cord vibration between the voiced and the voiceless stop consonants /b/ and /p/, and between the fricatives /s/ and /h/ are described, with special reference to the spectrum characteristics of the inverse-filtered source wave of each consonant.

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Reaction times to a phoneme /k/ in time-compressed (×0.5), normal (×1.0), and timeexpanded (×2.0) Japanese speech were measured to clarify how lexical facilitation of phoneme perception is related to phoneme position in a word/nonword and to the time elapsed from the onset of a word/nonword. The large difference in reaction times between words and nonwords was evident in later phoneme positions at long elapsed times in the time-expanded stimuli. However, this difference in the later phoneme positions became smaller or disappeared at short elapsed times in the time-compressed stimuli. In addition, even at the same elapsed time, there was a difference in reaction times when the phoneme position was late, but not when it was early. These results indicate that both the elapsed time and the phoneme position contribute to the lexical facilitation of phoneme perception.

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Ultrasonic probes with high resolution in the near sound field have been required for ultrasonic diagnostic and non-destructive testing equipments. The meniscus transducer of new type treated in this paper is expected to have such properties, because this transducer has the features of focusing in the near sound field and of damping effect by itself. For detecting small objects in the near field, the authors successfully fabricate a linear array probe using the meniscus transducers. Some characteristics of the probe are investigated to prove the suitability of detecting small objects in the near field.

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An investigation was conducted to ascertain the sound pressure levels of home electric appliances in actual situations, what the ideal levels were, and the level considered to be unacceptable. Added to this, the question of what amount purchasers considered it reasonable to pay for noise reduction. It was found that impression of the “actual, ” “ideal” and “intolerable” levels of sounds from home electric appliances could be obtained by psychoacoustical experiments. The results showed that there was a uniform difference of about 10dB between the three levels for the sounds used in the experiment. Subjects also suggested the acceptable cost of noise reduction in home electric appliances. Interesting information was also obtained concerning what kinds of electric appliances housewives wanted to have, what performance they expected, and what factors might contribute to the selection of electric appliances.

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This paper presents a practical prediction or transformation method from L_x data to L_eq value, especially for the road traffic noise at night with a small traffic volume. The nonlinear relationship between L_x and L_eq is grasped in principle by introducing a probabilistic neural network. Finally, the validity of the proposed method is experimentally confirmed too by applying it to the actually observed road traffic noise at night.

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