THE ACOUSTIC SATURATION AND HIGH FREQUENCY MODULATION IN HIGH INTENSITY SOUND

The sound pressure level received at a distance from a source will reach an upper limit when the source level is inereased. This condition is termed as saturation and the upper limit reached is said to be the saturated sound pressure level. On the assumption that the total attenuation suffered by the finite-amplitude simple waves is caused by the shock formation and an air absorption and by considering the divergent of the equiphase surface, a general expression of transmission is obtained for finite-amplitude simple waves and formulae found for saturation level. Experiments were carried out for finite-amplitude plane wave in a tube. The results agree better with the present theoretieal predietion than the weak shock theory. In experimental results, one observes clearly the gradual saturation of simple waves and high frequency modulations on the sawtooth waveform.