In many such languages, obstruents are realized as voiced in voiced environments, such as between vowels or between a vowel and a nasal, and voiceless elsewhere, such as at the beginning or end of the word or next to another obstruent. That is the case in Dravidian and Australian languages and in Korean but not in Mandarin or Polynesian. Usually, the variable sounds are transcribed with the voiceless IPA letters, but for Australian languages, the letters for voiced consonants are often used.

It appears that voicelessness is not a single