Introduction

Abstract

Acoustics, the science of sound, describes the phenomenon of mechanical vibrations and their propagation in solid, liquid or gaseous materials. Empty space knows no sound because it is the particles of matter themselves which vibrate, in contrast for instance to the oscillations of light or other electromagnetic waves where the electric and magnetic state of the space oscillates. In air a sound wave moves a discrete volume of air back and forth around its neutral position, whereas a light wave has no influence on its state of rest or motion.