8 Perception of sound: Overview

Sound sources- tuning forks, the strings on a guitar, your larynx when you speak, the cone of a stereo speaker- vibrate. These objects push against the nearby air molecules and force them to vibrate. Those molecules push on the molecules near them and so on. The disturbances in the air travel outward in all directions and eventually reach some sort of detector- like a microphone or a human ear. When the air molecules near the detector vibrate, the sound detector often converts the mechanical vibrations in electrical ones that can be recorded and/or processed. Vibrations that reach the human eardrum get turned into electrical impulses that your brain interprets as sound.

The characteristics of vibrations at the ear play a key role in what we hear. This chapter focuses on the link between characteristics of vibrations- like frequency, amplitude and spectral content- and what humans hear.