Diffraction of plane sound wave incident upon a 90° wedge with arbitrary surface impedance is analyzed on the basis of Maliuzhinets' solution of the sound diffraction by an impedance wedge. The diffraction coefficient is modified to yield a simple expression which shows the impedance dependence of the diffracted field explicitly. A uniform asymptotic solution is given for the diffraction field near shadow boundary and reflection boundary. Some numerical examples are given to investigate the dependence of diffracted field on the surface impedance. Experimental results are also given for a wedge composed of plywood panels with the absorptive surface using glass wool boards. Both numerical and experimental results show good agreement in representing the trends in excess barrier attenuation due to the impedance surface.

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A method for selective detection of the second harmonic component generated at the focal region in a focused sound field due to the local nonlinear properties of medium is discussed. The phase shift of sound waves passing through the focus offers the principle of the present method. Assuming a source with a Gaussian profile excitation to avoid the edge diffraction, the effect of an inserted sample with a nonlinearity parameter different from that of surrounding liquid (water) is theoretically analyzed. The experiment employing a sample of benzyl alcohol shows the validity of the theory. The quadrature component of the second harmonic which differs in phase by π/2 radians from that of non-diffraction case corresponds well to the second harmonic generation at the focus, i.e. the nonlinear property of the sample within the focal region.

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This paper reports on the relation between voice intensity I*[dB] and mean airflow rate U [cm³/s] during the sustained phonation of a vowel-like sound. In the experiment each subject was asked to increase the intensity of phonation in gradual steps from a “comfortable” level to higher degrees; without exceeding a level where discomfort would have resulted. During this process the fundamental frequency (F₀) was kept constant. A total of 18 sets of data were obtained from 4 females and 7 males. Values of intensity and airflow rate were plotted on an I* vs. U* display, where U* indicates dB representation of U, i.e. U* =20 log (U/U₀), where U₀=1cm³/s. The relationship between I* and U* were represented both by a single line, and several line segments (up to three). Each line is represented by I* =AU* +B, and values of A were examined statistically for both -single and three line approximations. A value of A=2 was observed most frequently for the single line approximations, regardless of female/male distinction. For the three line approximations, the median of A was 1.5, 2.9, and 2.0, as obtained for low, edial, and high intensity regions, respectively. Overall patterns for the three line approximations were also examined, and it was found that S-shaped patterns appeared most frequently. These results will be useful for discussing the laryngeal control during the phonation.

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The purpose of this investigation is to examine effects of the interaural crosscorrelation (IACC), relating to subjective diffuseness of sound field, on the auditory-evoked potential (AEP). Using a one-third octave bandpass-filtered noise with the center frequency of 500 Hz as a source signal, IACC ranging from 0.95 to 0.1 was controlled. AEPs to a pair of sounds, i.e., reference sound (IACC =0.95) and test sound (IACC =0.95, 0.75, 0.50, and 0.1), which were presented alternately, in order to compare the result with the subjective diffuseness function [Y. Ando and Y. Kurihara, J. Acoust. Soc. Am. 80, 833-836 (1986)], were recorded from temporal areas. The information related to the IACC in response to test sounds appeared in latency components, in which a tendency of increasing latency with decreasing the magnitude of IACC was observed. It is noteworthy that the relationship between IACC and latency of AEP is found to be linear. These results may evidence of the existence of a set of neurons or a mechanism in the auditory brain system which respond to the IACC of sound field.

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A detailed mechanism of the chemical dissolution of calcium salt crystal and the actions of ultrasound on the acceleration in the system were clarified by the kinetic study on the chemical dissolution of gypsum in EDTA solution with the irradiating of ultrasoundand the stirring of the solution. The transfer-process of the intermediate complex on the surface of calcium salt crystal to the liquid phase is another rate-determining step, besides the formation-process of the intermediate complex on the surface. Ultrasound acts as follows ;(i) the formation of the intermediate complex is accelerated by theincrease in the number of collision between a calcium ion on the crystal surface and chelating agent ion, ligand, in the liquid phase with the ultrasonic power ;(ii) the ultrasonic straight flow increases the replacement-rate of the solution in the vicinity of the crystalurface by that in the bulk, which accelerates the formation of intermediate complex on the crystal surface and the transfer of the complex to liquid phase;(iii) the chemical dissolution on the inside of many pinholes on the crystal surface is also made by theultrasonic microstream of the solution.

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The auditory evoked potential (AEP) and the subjective preference for sound field were investigated as a function of the time delay (Δ t₁) of sound field with single reflection. The stimulus was a female voice with 0.9 s duration and the delay was adjusted in a range of 0 to 125 ms. The information related to subjective preference appeared in the latency components, in which a relatively long-latency responses was observed at the most preferred delay. It is shown that the difference of latencies of AEPs over both hemispheres in response to a pair of sound fields with different delay contains almost the same information that is expressed by the subjective preference value obtained from paired comparison tests.

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