Sibilant consonant
A
sibilant is a type of
fricative or
affricate, made by directing a jet of air through a narrow channel towards the sharp edge of the
teeth.
The term
sibilant is often taken to be
synonymous with the term
strident, though this is incorrect - there is variation in usage. The term
sibilant tends to have an
articulatory or
aerodynamic definition involving the production of
aperiodic noise at an obstacle.
Strident refers to the
perceptual quality of
intensity as determined by
amplitude and
frequency characteristics of the resulting sound (i.e. an
auditory, or possibly
acoustic, definition).
Sibilants are louder than their non-sibilant counterparts, and most of their acoustic energy occurs at higher frequences than non-sibilant fricatives. has the most acoustic strength at around 8,000 Hz, but can reach as high as 10,000 Hz. has the bulk of its acoustic energy at around 4,000 Hz, but can extend up to around 8,000 Hz.
The spin-off terms
shibilant, and rarely
thibilant, are used to describe particular kinds of sibilant.
Of the sibilants, the following have
IPA symbols of their own:
Alveolar:
* , (either
apical or
laminal).
Postalveolar:
* , (
Palato-alveolar: that is, "domed" (partially palatalized) postalveolar, either laminal or apical)
* , (
Alveolo-palatal: that is, laminal
palatalized postalveolar; these are equivalent to )
* , : (
Retroflex, which can mean one of three things: (a) non-palatalized apical postalveolar, (b) sub-apical postalveolar or pre-palatal, or (c) non-palatalized laminal ("flat") postalveolar, sometimes transcribed or .
Diacritics can be used for finer detail. For example, apical and laminal alveolars can be specified as
vs ; a
dental (or more likely
denti-alveolar) sibilant as ; a palatalized alveolar as ; and a generic postalveolar as , a transcription frequently used when none of the above apply (that is, for a laminal but non-palatalized, or "flat", postalveolar). Some of the
Northwest Caucasian languages also have a
closed laminal postalveolar, without IPA symbols but provisionally transcribed as .
Only the alveolar and palato-alveolar sibilants are distinguished in
English; the former are apical, while the latter are slightly
labialized and generally called simply "postalveolar": .
Polish and
Russian have laminal denti-alveolars, palatalized denti-alveolars, flat postalveolars, and alveolo-palatals, ; whereas
Mandarin has apical alveolars, flat postalveolars, and alveolo-palatals, .
Few languages distinguish more than three series of sibilants without
secondary articulation, but
Ubykh has four series of plain sibilants, , and the Chinese dialect of Qinan, in
Shandong province, is said to have five.
Toda has a laminal alveolar, an apical postalveolar, laminal domed postalveolars, and sub-apical palatals. Since two of these could be called 'retroflex',
Ladefoged &
Maddieson 1996 have resurrected the old IPA diacritic for retroflex, the underdot, for apical retroflexes, and reserve the letters <> for sub-apical retroflexes. Thus the Toda sibilants can be transcribed , although the official IPA symbols are also sufficient. (In some publications the underdot and underbar are interchanged.)
Some authors, as for instance
Chomsky &
Halle (1964), group and as sibilants. However, they do not have the grooved articulation and high frequencies of other sibilants, and most phoneticians (for instance by Ladefoged & Maddieson 1996), continue to group them together with the
bilabial fricatives ,
] as non-sibilant
anterior fricatives. Some researchers judge to be strident in one language, e.g. the African language Ewe, as determined by experimental measurements of amplitude, but as non-strident in English.
The nature of
sibilants as so-called 'obstacle fricatives' is complicated - there is a continuum of possibilities relating to the angle at which the jet of air may strike an obstacle. The grooving often considered necessary for classification as a
sibilant has been observed in ultrasound studies of the tongue for supposedly
non-sibilant voiceless alveolar non-sibilant fricative (Stone and Lundberg, 1996, Journal of the Acoustical Society of America, vol. 99: 3728-3737). More research on the phonetic bases of the terms sibilance and stridency, and their interrelationship, is required.
*
strident vowels
