抄録
As shown in previous papers, the beat frequency, its clearness, and duration of remaining tone were freely adjusted by means of local loading and local paring. The research was related only to the fundamental tone. The objective of this paper is to find a method of adjusting the timbre of a Japanese bell. We investigated how the striking rod effected on the timbre of the Japanese bell, in which many overtones were related to the timbre. We tried a kind of model experiment in order to clarify the relation between the material and mass of striking rod and the timbre of the Japanese bell. Namely, we used a block of material in place of the striking rod and striked the bell by changing the material, speed and mass of block. We measured the duration of time that the block was in contact with the bell and the rebound coefficient. From these results the elastic property of the striking rod was obtained. Moreover, the timbre was indicated by the difference of sound spectra by changing the material of the block. In this case, the pattern of sound spectrum was shown by the strength of partial tones, which were divided into three parts, namely the fundamental tone, the first overtone and other tones. These sound spectra were obtained by means of a 1/3 octave analyzer. The results obtained from the above experiments are as follows: (1) The touching time of aluminum is smaller than in order materials. The value is under 10×10^<-3> second and does not change even though the striking speed is changed. The rebound coefficient is smaller than that of other materials, being evaluated under 0. 1. The pattern of sound spectrum is of the roof type, in which the sound level of the first overtone is larger than those of the fundamental tone and the other tones. (2) The touching time of bakelite is almost the same as in aluminum, but the rebound coefficient is large raging 0. 2〜0. 25. The sound level of other overtones is much smaller than that of the first overtone. (3) The touching times of rubber and cork are larger than in the other materials and the values are 50×10^<-3> second and 25×10^<-3> second respectively. The rebound coefficients are large being evaluated at 0. 3〜0. 5. In the sound spectrum, the level of the fundamental tone is higher than in the other tones. (4) The touching time of woods-hemlock-spruce, a kind of cypress, and Japanese cypress and Japanese cedar-is 10×10^<-3> second. The value remains almost constant by changing the speed and mass of the striking block. The pattern of sound spectrum is of the roof type and different from those of rubber and cork. The above experiment is a kind of model experiment, from which we obtained the relation between the timbre of bell and the material of striking rod. Next, we shall investigate how the striking rod in general use effects on the timbre of Japanese bell.
