Vibration of about 20 per second us the lowest to which the
ear can respond to an intensity level of 10-16 watt /cm2 . At 15 ,000 vps ,
the sound becomes a hiss . Higher than 20 ,000 vps sound becomes
inaudible . The range from 20-20 ,000 is called audio frequency , and
frequencies higher than 20 ,000 per sec are called radio...