Sound and Acoustics: Introduction
Sound is a longitudinal pressure wave which propagates through an elastic medium. Molecules are displaced and due to the elastic nature of the medium they tend to spring back to their original position. The restoring force is due to a change in pressure (for sound waves in fluids) or stress (in the case of solids).
In the sections that follow we will consider how these waves moves through the elastic medium. Following that we will introduce some of the basic concepts in acoustics.