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Phonetics has three main branches:
- articulatory phonetics, concerned with the positions and movements of the lips, tongue, and other speech organs in producing speech;
- acoustic phonetics, concerned with the properties of the sound waves; and
- auditory phonetics, concerned with speech perception.
Of all the speech sounds that a human vocal tract can create, different languages vary considerably in the number of these sounds that they use. Languages can contain from 2 (Abkhaz) to 55 (Sedang) vowels and 6 (Rotokas) to 117 (!Kung) consonants. The total number of phonemes in languages varies from as few as 10 in the Pirahã language, 11 in Rotokas (spoken in Papua New Guinea), and 12 in Hawaiian, to as many as 141 in !Xu (spoken in southern Africa, in the Kalahari desert). These may range from familiar sounds like /t/, /s/ or /m/ to very unusual ones produced in extraordinary ways (see: clicks, phonation, airstream mechanism). The English language has about 13 vowel and 24 consonant phonemes (depending upon dialect), some of which have multiple allophones. This differs from the lay definition based on the Latin alphabet, where there are 21 consonants and 5 vowels (although sometimes y and w are included as vowels).
Phonetics was studied as early as 2500 years ago in ancient India .