For some authors, only the termresonant is used with this broader meaning, whilesonorant is restricted to the consonantal subset—that is, nasals and liquids only, notvocoids (vowels and semivowels).[2]
Whereasobstruents are frequentlyvoiceless, sonorants are almost always voiced. In thesonority hierarchy, all sounds higher thanfricatives are sonorants. They can therefore form thenucleus of asyllable in languages that place that distinction at that level of sonority; seeSyllable for details.
Sonorants contrast withobstruents, which do stop or cause turbulence in the airflow. The latter group includesfricatives andstops (for example,/s/ and/t/).
Among consonants pronounced in the back of the mouth or in the throat, the distinction between anapproximant and a voiced fricative is so blurred that no language is known to contrast them.[citation needed] Thus,uvular,pharyngeal, andglottal fricatives never contrast with approximants.
Voiceless sonorants are rare; they occur asphonemes in only about 5% of the world's languages.[3] They tend to be extremely quiet and difficult to recognise, even for those people whose language has them.
In every case of a voiceless sonorant occurring, there is a contrasting voiced sonorant. In other words, whenever a language contains a phoneme such as/ʍ/, it also contains a corresponding voiced phoneme such as/w/.[citation needed]
One European language with voiceless sonorants isWelsh. Itsphonology contains a phonemicvoiceless alveolar trill/r̥/, along with three voiceless nasals: velar, alveolar and labial.
Another European language with voiceless sonorants isIcelandic, with [l̥ r̥ n̥ m̥ ɲ̊ ŋ̊ ȷ̊] for the corresponding voiced sonorants [l r n m ɲ ŋ j].
Voiceless sonorants have a strong tendency to either revoice or undergofortition, for example to form africative like/ç/ or/ɬ/.[example needed]
In connected, continuous speech inNorth American English,/t/ and/d/ are usuallyflapped to[ɾ] following sonorants, including vowels, when followed by a vowel or syllabic/l/.[6]
^Keith Brown & Jim Miller (2013)The Cambridge Dictionary of Linguistics
^Ken Pike,Phonetics (1943:144). "The sonorants are nonvocoid resonants and comprise the lateral resonant orals and resonant nasals (e.g. [m], [n], and [l])."
^Ian Maddieson (with a chapter contributed by Sandra Ferrari Disner);Patterns of sounds; Cambridge University Press, 1984.ISBN0-521-26536-3
^"Consonants". UCL DEPT OF PHONETICS & LINGUISTICS. September 19, 1995. RetrievedJuly 30, 2012.
^Greene, David (1973). "The Growth of Palatalization in Irish".Transactions of the Philological Society.72:127–136.doi:10.1111/j.1467-968X.1973.tb01017.x.