The auditory sensations produced by some AM-tones were studied by evaluating the masking values and based on the experimental results, a masking analog simulator was proposed for the logical estimation of the loudness of AM-tone. A 3kHz-5msec-signal was applied at various phases against a white noise masker whose amplitude was changed with one of the patterns of step, sinusoidal and M-sequence functions. From the viewpoint of the control theory, five non-linearities of AM-masking characteristics were assumed to exist and we reached the following conclusions: The system responsible for the masking of AM-tone can be simulated by a 2nd-order system with the damping factor as the function of its input value. The masking by a monosyllable /ta/ increased markedly at the stage of consonant, which is also proved by our simulator. This analog simulator is valuable for the analyses of the vocal-feature-extracting-process.
Behavior of fluid with main flow in a circular tube, in which progressive waves are propagating, is analyzed. We assume that the fluid is viscous and in-compressible and axisymmetric travelling sinusoidal waves of moderate amplitude are imposed on the wall of the tube. A perturbation method' is adopted for the solution. The velosity ratio of the vibration velocity of the wall to the maximum velocity of the main flow is chosen as a parameter, and the Navier-Stokes equation is developed up to the second order of the velocity ratio. The results show that the solution is characterized by a non dimensional number for the case of a wave which has a long wavelength, and that the mean axial velocity induced in the tube is dominated by three critical terms.
A uniform bar vibrator has simple structure and is used widely for various kinds of resonators and me chanical filters. However, it is difficult to miniaturize it in low frequencies because of its resonant frequency constant a=4. 730. In this paper, the S-type bar vibrator is analyzed by the mechanical equivalent network, and compared with the uniform bar vibrator. As a result, it is found that the S-type bar has several advantages for miniaturization in low frequencies ; (D The resonant frequency of the S-type bar is lower about 90s than that of the uniform bar with the same length, (2) In comparison the area (volume) occupied these vibra tors, the S-type bar is also more profitable than the uniform bar. The resonant frequencies for various dimensions of the S-type bar vibrator are calculated Consequently, the optimally minimized dimensions of the vibrator for low frequencies are derived schemati cally. The vibration modes and the location of nodal points of the vibrator are analyzed, and the structure which allows easy supporting is discussed.
This paper is concerned with the problem of realizing a desired directivity characteristic approximately by controlling electric power given to individual ultra sonic transducers mounted on a rigid hemisphere in: sea water. The objective function to be minimized is the sum of squares of the differences between the: desired and real directivity characteristics at a number of preassigned points. An iterative algorithm is given and two illustrative examples demonstrate the effectiveness of the algorithm using a digital computer.