What is a loudspeaker?
1.1 A brief look at the concept
Before answering the question posed by the title of this chapter, perhaps we had better begin with the question “What is sound?” According to Fahy1 “sound may be defined as a time-varying disturbance of the density of a fluid from its equilibrium value, which is accompanied by a proportional local pressure, and is associated with small oscillatory movements of the fluid particles”. The difference between the equilibrium (static) pressure and the local, oscillating pressure is known as the sound pressure.
Normally, for human beings, the fluid in which sound propagates is air, which is heavier than most people think – it has a mass of about 1.2 kg per cubic metre at a temperature ...