Tocharian phonology

Phonetically, Tocharian is a "centum" Indo-European language, meaning that it merges the palatovelar consonants of Proto Indo-European with the plain velars (*k, *g, *gʰ). Centum languages are mostly found in western and southern Europe (Greek, Italic, Celtic, Germanic). In that sense, Tocharian (to some extent like the Greek and the Anatolian languages) seems to have been an isolate in the "satem" (i.e. palatovelar to sibilant) phonetic regions of Indo-European-speaking populations. The discovery of Tocharian contributed to doubts that Proto-Indo-European had originally split into western and eastern branches.

Vowels
Note that, although both Tocharian A and Tocharian B have the same set of vowels, they often do not correspond to each other. For example, the sound a did not occur in Proto-Tocharian. Tocharian B a is derived from former stressed ä or unstressed ā (reflected unchanged in Tocharian A), while Tocharian A a stems from Proto-Tocharian /ɛ/ or /ɔ/ (reflected as /e/ and /o/ in Tocharian B), and Tocharian A e and o stem largely from monophthongization of former diphthongs (still present in Tocharian B).

Diphthongs
Diphthongs occur in Tocharian B only.

Consonants
The following table lists the reconstructed phonemes in Tocharian along with their standard transcription. Because Tocharian is written in an alphabet used originally for Sanskrit and its descendants, the transcription of the sounds is directly based on the transcription of the corresponding Sanskrit sounds. The Tocharian alphabet also has letters representing all of the remaining Sanskrit sounds, but these appear only in Sanskrit loanwords and are not thought to have had distinct pronunciations in Tocharian. There is some uncertainty as to actual pronunciation of some of the letters, particularly those representing palatalized obstruents (see below).


 * 1)  is transcribed by two different letters in the Tocharian alphabet depending on position.  Based on the corresponding letters in Sanskrit, these are transcribed  (word-finally, including before certain clitics) and n (elsewhere); but it should be noted that  represents /n/, not /m/.
 * 2) The sound written  is thought to correspond to a palatal stop  in Sanskrit.  The Tocharian pronunciation  is suggested by the common occurrence of the cluster śc, but the exact pronunciation cannot be determined with certainty.
 * 3) The sound written  corresponds to retroflex sibilant  in Sanskrit, but it seems more likely to have been a palato-alveolar sibilant  (as in English "ship"), because it derives from a palatalized /s/.
 * 4) The sound ṅ  occurs only before k, or in some clusters where a k has been deleted between consonants. It is clearly phonemic because sequences nk and ñk also exist (from syncope of a former ä between them).