phonologist
A scholar who studies the sound systems of languages. Used in academic contexts.
As a phonologist, he studies the vowel system of Japanese.
音声学者 focuses on the physical production and perception of speech sounds (phonetics), while 音韻学者 studies the abstract sound patterns and systems (phonology).
Compound of 音韻 (phoneme, sound pattern) + 学者 (scholar). The exact historical derivation is uncertain, but the term follows standard academic word formation patterns.