linguistics - Is there such a thing as an unvoiced vowel?

I can't think of any and google has not been helpful.

Answer

Voiceless vowels are quite possible, and occur in one way or another in many languages.
After all, all vowels and all consonants that are whispered are ipso facto voiceless.
Whisper [a] and you have pronounced a voiceless vowel.

However, the overwhelming majority of vowel sounds in speech are voiced, since vowel formants are modifications of a voiced airstream from the larynx. Exceptions to this rule fall into a number of categories.

• in some languages, like Japanese, some vowels become voiceless in some environments
  (in Japanese, high vowels /i/ and /u/ are devoiced between voiceless consonants)


• in some languages, like English, voiceless vowels are allophones of a consonant phoneme
  (English /h/ is a voiceless vocal onset, a voiceless version of whatever vowel it precedes)


• in some languages (Acehnese, for instance) some vowel phonemes are contrastively voiceless
  (this is quite rare, however -- most voiceless vowels are conditioned rather than contrastive.)