|Budget Amount *help
¥1,000,000 (Direct Cost : ¥1,000,000)
Fiscal Year 1997 : ¥200,000 (Direct Cost : ¥200,000)
Fiscal Year 1996 : ¥800,000 (Direct Cost : ¥800,000)
The noise produced by scratching a glass board by a nail or a metal fork causes a annoying impression. We call that kind of noise "an annoying sound", and we have analyzed and synthesized that sound in order to investigate its physical property. Since it is generated frictionally, the physical model of frictional vibration system such as bowed string are considered and the kinetic equations describing the system are solved. The values of some parameters (e.g., coefficient of friction between materials and velocity of movement) affect the characteristics of the system, and the change of period of vibration occurs abruptly and discontinuously. The chaotic phenomena also occurs in the transitional region. The realistic sound can be generated by adding random values to the values of the parameters said above. One of the essential properties for the annoying sound is an irregularity of the period of stick-slip phenomenon, and that period depends on the value of random variable. The waveform of about 1 second duration are generated by solving the kinetic equations, and changes of stick-slip periods are observed. This waveform is given as an impulse train. The impulse response of a glass board is measured, and the final waveform of glass-scratching sound is synthesized by convolving the impulse response to the impulse train. Since there exist some problems for the measurement of impulse response of a glass board (e.g., the way of impulsive attack to the glass board or the use of anechoic room, ) the annoying impression is not achieved perfectly.