PHONETICS

The study of the characteristics of human sound-making, especially of those sounds used in speech; generally divided into articulatory, acoustic, and auditory branches. "Both linguistics and phonetics are grounded in a basic interest in the nature of human communication. . . .
"Linguistics contributes to phonetics its phonological understanding of the distinctive patterns that make up the coded, conventional aspects of speech which differentiate individual words and other units of spoken language. Phonetics contributes to linguistics its phonetic understanding of the production and perception of the detailed artefacts of speech that embody those significant phonological patterns. Each contribution is complemented by the other."
(John Laver, "Linguistic Phonetics." The Handbook of Linguistics, ed. by Mark Aronoff and Janie Rees-Miller. Blackwell, 2001)
"[Phonetics] is divided into three main branches, corresponding to these three distinctions:

- articulatory phonetics is the study of the way the vocal organs are used to    produce speech sounds
- acoustic phonetics is the study of the physical properties of speech sounds
- auditory phonetics is the study of the way people perceive speech sounds"