Abstract
A laboratory measurement of the attenuation constant of sound waves travelling through rock was carried out. The so-called free vibration method was employed for this purpose. The travelling and oscillating longitudinal sound waves were excited in a long boring-core specimen of rock by means of an impact of small steel ball tied at one end of the specimen which was horizontally suspended by strings. The fundamental frequency of the oscillating waves was decided by the length of the bar. Observation was also enacted of the damped free oscillation of the sound waves.
The reasonable attenuation constants and Q values have been obtained from several rock specimens. The Q's which have been directly calculated from the attenuation constants are substantially independent of frequency, but the Q of the Kuzuu (in Tochigi Prefecture) limestone is evidently dependent on the wave frequency.
