Mitsuhide Sasaki

Apparatus for reducing noise in a closed space having divergence detector

An automatic sound suppression system is automatically disengaged whenever noise in an area and generated counter noise deviate in their reverse phase relationship or if the amplitude of the counter noise deviates from that of the noise. The system can also be automatically disengaged whenever divergence prediction means predicts that sounds of the noise and the counter noise diverge or whenever divergence prediction means predict that sounds of the noise and the counter noise are about to diverge. The system can also operate as a vibration reducing apparatus which is also automatically disengaged whenever divergence prediction means predicts that a vibration and a generated countervibration diverge.