November 2002
Intermediate to advanced
848 pages
19h 59m
English
Sound occurs because of a vibration of molecules that arrives at our ears as a wave. Typically the molecules vibrating are air, but sound also propagates through other mediums including liquids and solids.
The rate at which the molecules vibrate determines the pitch of the sound, whereas the amount (amplitude) of vibration determines the volume. The rate of vibration is known as the frequency and is measured in hertz. One hertz represents one complete cycle or vibration per second. A person with unimpaired hearing is able to perceive sound from around 20Hz to around 20KHz (20,000 Hertz). However, human perception isn't evenly distributed across that frequency range: Far more attention or emphasis is given to the lower frequency range ...