Abstract
The sounds of 115 Temple Bells are analysed and the frequencies of the fundamental and partial tones in their sounds are measured. The variations in the structure of sound spectrum concerning the frequencies distribution of partial tones with the lapse of periods are clarified. Following results are obtained. The intervals between the frequencies of adjacent partial tones are widest in the bells of Nara Period on the average and become narrower with the lapse of periods. In the bells of Nanpokucho Period they become narrowest, and after that there is the tendency to increase gradually. These variations with the lapse of periods are chiefly caused by the increase in thickness of "Koma-no-tsume"(Hoof-shaped lowest brim of the bell body) and the decrease in thickness of the upper portion of bell body as the periods go by. Considering these changes in the thickness of bell body, the empirical formulae clarifying the variations are derived.
