, the term voiceless
describes the pronunciation of sounds when the larynx
does not vibrate. Phonologically, this is a type of phonation
, which contrasts with other states of the larynx, but some object that the word "phonation" implies voicing, and that voicelessness is the lack
of phonation. (See phonation
The International Phonetic Alphabet has distinct letters for many voiceless and modally voiced pairs of consonants (the obstruents), such as , and also a diacritic for voicelessness, [ ̥] (the under-ring) that can be used with letters for prototypically voiced sounds, such as vowels and nasal consonants: . (The ring is placed above letters with descenders, as with [ŋ̊].)
Voiceless vowels and other sonorants
are those sounds, such as vowels and nasal consonants
, which are voiced in most of the world's languages. However, in some languages sonorants may be voiceless, usually allophonically
. For example, the Japanese
is pronounced [su̥kijaki]. This may sound like [skijaki] to an English speaker, but the lips can be seen compressing for the [u̥]. Something similar happens in English with words like peculiar
[pʰə̥ˈkjuːliɚ] and particular
Sonorants may also be contrastively voiceless, not just voiceless due to their environment. Tibetan, for example, has a voiceless /l̥/ in Lhasa, which sounds similar to, but is not as noisy as, the voiceless lateral fricative /ɬ/ in Welsh, and which contrasts with a modally voiced /l/. Welsh contrasts several voiceless sonorants: , , , and , the latter found in the name Rhiannon.
On the other hand, although contrastively voiceless vowels have been reported several times, they have never been verified (L&M 1996:315).
Lack of voicing contrast in obstruents
Many languages lack a distinction between voiced and voiceless obstruents. This is nearly universal in Australian languages
, but is widely found elsewhere, for example in Mandarin Chinese
, and the Polynesian languages
. Consider Hawaiian
, which has a /p/ and /k/, but no /b/ or /g/. In many such languages (though not Polynesian), 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. Usually these sounds are transcribed with the voiceless IPA letters, though in Australia the letters for voiced consonants are sometimes used.
It appears that voicelessness is not a single phenomenon in such languages. In some, such as the Polynesian languages, the vocal cords are required to actively open to allow an unimpeded (silent) airstream. In others, such as many Australian languages, voicing ceases during the hold of a plosive (few Australian languages have any other kind of obstruent) because airflow is insufficient to sustain it, and if the vocal cords open this is due to passive relaxation. Correspondingly, Polynesian plosives are reported to be held for longer than Australian plosives, and are seldom voiced, whereas Australian plosives are prone to having voiced variants (L&M 1996:53).