In this paper, a general description of the acoustic correlate of nasality is quantitatively discussed from a perceptual point of view. The acoustic correlate of nasality is assumed to be the degree of spectral difference between nasal sounds and non-nasalized vowels. An active model to extract the difference as nasality parameters is assumed as a functional model for the extraction of nasality. The correspondence is examined between the nasality parameters and the perceptual judgment on nasalization. Fairly good correspondence is obtained by considering the weighted function in the spectral domain and the frequency region of the spectral difference.
This paper describes the design method and the conditions for miniaturizing the diaphragm area of a DC biased and electret directional condenser microphone, that is, the most important things in order to miniaturize the microphone. First, the relation between the diaphragm area and the major characteristics of the microphone, that is, the frequency range, stability, inherent noise, nonlinear distortion and dynamic range is theoretically analyzed. On the basis of the results obtained, the design formulas are derived, by which the minimum effective area of the diaphragm to satisfy the desired fundamental characteristics mentioned above.
This paper deals with theoretical and experimental considerations of the changes in resonant frequency f, and quality factor Q of a vibrator with input energy level in low frequencies, for the purpose finding the limit of its miniaturization and stability. Firstly, flexural bars of uniform and stepped shape made of elinver alloy are considered. It is revealed that the step-formed bars are not suitable for vibrators of small size and high stability. The flexural uniform bar designed under consideration of f_r and Q in low input energy level and its changes in high level are also described. Furthermore, the flexural composite type bars on which a piezo-ceramic element is bonded are considered. The influences of the adhesive layer on changes in f_r, and Q are found experimentally to be marked for Q, but insignificant for f_r. Secondly, similar considerations are applied to longitudinal vibrators. Finally, it is proposed that a new figure of merit should be adopted for overall evaluation of low frequency vibrators. This is because, although many vibrators are developed so far no reasonable method is known that can be applied to the evaluation of vibrators with respect to dimensional smallness and high stability. By utilising the new figure of merit mentioned in this paper, low frequency vibrators can be ranked with respect to its stability and smallness in size.
The effects of electric fields on ultrasonic attenuation in nematic and cholesteric liquid crystals was investigated. It is found that the ultrasonic attenuation of the nematic liquid crystal MBBA, when the propagation direction of the sound waves is parallel to the direction of applied electric field, decreases as the field increases for small fields, while above a certain field intensity it begins to increase reaching a saturation value. When the propagation direction of the sound waves is perpendicular to the electric field, the change occurs in the opposite way, since MBBA has a negative electric characteristic. On the other hand, for positive N. Mix. , the change in attenuation varies monotonically. These phenomena can be explained by molecular alignment together with the ultrasound scattering due to the fluctuation of the liquid density. The magnitude of the ultrasonic attenuation in cholesteric liquid crystals is a few-tenths of that in nematic liquid crystals.