Proto-Dravidian historical phonology

Vowels: Proto-Dravidian contrasted between five short and long vowels: *a, *ā, *i, *ī, *u, *ū, *e, *ē, *o, *ō. The sequences *ai and *au are treated as *ay and *av (or *aw)

Consonants: Proto-Dravidian is reconstructible with the following consonantal phonemes (Subrahmanyam 1983:p40, Zvelebil 1990, Krishnamurthi 2003):

The alveolar stop  in many daughter languages developed into an alveolar trill. The stop sound is retained in Kota and Toda (Subrahmanyam 1983). Malayalam still retains the original (alveolar) stop sound in gemination. (ibid). In Old Tamil it took the enunciative vowel like the other stops. In other words, (or ) did not occur word-finally without the enunciative vowel (ibid).

Velar nasal occurred only before  in Proto-Dravidian (as in many of its daughter languages). Therefore it is not considered a separate phoneme in Proto-Dravidian. However, it attained phonemic status in languages like Malayalam, Gondi, Konda and Pengo due to the simplification of the original sequence * to. (Subrahmanyam 1983)

The glottal fricative has been proposed by Bh. Krishnamurthi to account for the Old Tamil Aytam (Āytam) and other Dravidian comparative phonological phenomena (Krishnamurthi 2003).