The Collaborative International Dictionary of English v.0.48:

Phonetician \Pho`ne*ti"cian\ (f[=o]`n[-e]*t[i^]sh"an), n.
   One versed in phonetics; a phonetist.
   [1913 Webster]

WordNet (r) 3.0 (2006):

phonetician
    n 1: a specialist in phonetics

Moby Thesaurus II by Grady Ward, 1.0:

25 Moby Thesaurus words for "phonetician":
   dialectician, etymologer, etymologist, glossarist, glossographer,
   grammarian, grammaticaster, grammatist, lexicographer,
   lexicologist, linguist, linguistic scholar, linguistic scientist,
   linguistician, orthoepist, paleographer, philologaster, philologer,
   philologian, philologist, phonemicist, phoneticist, phonologist,
   semanticist, semasiologist