Transient response of wood for musical instruments and its mechanism in vibrational property

摘要

The tapping sound of wood, which included sitka spruce and maple used for musical instruments, and isotropic materials was analyzed into power spectra every one milliseconds and their transient characteristics were investigated. The variations of 1/3-octave band power spectra with time were visualized in three dimensions. The rise time T_r and the decrement rate were investigated at each 1/3-coctave band. The T_r decreased rapidly with increasing frequencies up to the first mode resonance regardless of the materials, and then the variation of T_r depended on the materials. The former depended only on frequency and the latter on flexural resonance intensity. Sitka spruce used for soundboards showed the high level up to the middle frequency range and then, decreased considerably the level by increasing considerably the internal friction and showed the fastest rising characteristic in the high frequency range. This characteristic in the high frequency range was attributed to the shear effect in which sitka spruce was the greatest.