affricate consonant afro-asiatic languages airstream mechanism alveolar consonant apical consonant approximant consonant back vowel basque language caucasus central consonant click consonant close vowel consonant cushitic languages ejective consonant endangered language epiglottal consonant flap consonant fricative consonant front vowel glottal consonant hadza language implosive consonant kenya labial consonant labialisation laminal consonant language language family language shift lateral consonant mid vowel nasal consonant obstruent open vowel pacific northwest palatal consonant pitch accent sandawe language south cushitic languages substratum trill consonant unicode velar consonant voice onset time vowel