Unfortunately, many of the machines that make our lifestyles possible today rely upon speed to maintain efficiency. It is impossible to reduce or eliminate many of these noise sources and we must rely upon containment to keep the noise from reaching our ears. Containment may be the placement of a physical barrier between us and the sound waves or the use of some device for canceling or attenuating the sounds close to the source. First let's make sure we understand the nature of sound waves. Sure everyone knows that sound travels through air just like ripples on a pond when you toss in a stone.
Water is incompressible .
The surface waves on the pond are formed when water bobs up and down. In this case gravity provides an elastic restoring force. Air, on the other hand, is compressible and a sound wave is a pressure pulse, i.e. an expansion and contraction of the air that radiates out in all directions from the initial disturbance. The speed of a surface water wave depends upon its size. A large wave propagates faster than a small wave.