ABSTRACT
Acoustic phonetics deals with the properties of sound as represented in variations of air pressure. A sound, whether its source is articulation of a word or an exploding cannon ball, disturbs the surrounding air molecules at equilibrium, much as a shove by a person in a crowded bus disturbs the standing passengers. The sensation of these air pressure variations as picked up by our hearing mechanisms and decoded in the brain constitutes what we call sound (see also AUDITORY PHONETICS). The question whether there was a sound when a tree fell in a jungle is therefore a moot one; there definitely were airmolecule variations generated by the fall of the tree, but unless there was an ear to register them, there was no sound.
