Sibilants (from ) are fricative and affricate consonants of higher amplitude and pitch, produced with a high velocity jet of air going on to strike the edge of some obstruction, such as the teeth and sometimes the lips. Examples of sibilants in English are the consonants at the beginning of words sip, zip, ship, and genre. The symbols in the International Phonetic Alphabet used to denote the sibilant sounds in these words are, respectively, . Sibilants have a characteristically intense sound, which accounts for their paralinguistic use in getting one's attention (e.g. calling someone using "psst!" or quieting someone using "shhhh!").
Overview In the alveolar hissing sibilants, such as , the tongue forms a narrow channel (groove) to focus the stream of air towards the teeth, resulting in a higher pitched and more intense sound. With the postalveolar hushing sibilants (occasionally called shibilants,Lisker, Leigh. 2001. Hearing the Polish sibilants [s š ś]: Phonetic and auditory judgements. In Grønnum, Nina & Rischel, Jørgen (eds.), To honour Eli Fischer-Jørgensen (Travaux du Cercle Linguistique de Copenhague XXX), 226–238. suggestive of their quality), such as , the tongue is flatter, and the resulting pitch lower.
A broader category is stridents, which also includes labiodental and uvular fricatives. Sibilants are a higher pitched subset of the stridents. The English sibilants are: Fricatives Affricates /tʃ, dʒ/ while the English stridents are:
as and are stridents but not sibilants because they are lower in pitch.
Some linguistics use the terms "stridents" and "sibilants" interchangeably to refer to the greater amplitude and pitch compared to other fricatives.
"Stridency" refers to the perceptual intensity of the sound of a sibilant consonant, or obstacle fricatives or affricates, which refers to the critical role of the teeth in producing the sound as an obstacle to the airstream. Non-sibilant fricatives and affricates produce their characteristic sound directly with the tongue or lips etc. and the place of contact in the mouth, without secondary involvement of the teeth.
The characteristic intensity of sibilants means that small variations in tongue shape and position are perceivable, with the result that there are many sibilant types that contrast in various languages.
Acoustics Sibilants are louder than their non-sibilant counterparts, and most of their acoustic energy occurs at higher frequencies than non-sibilant fricatives – usually around 8,000 Hz.
Sibilant types All sibilants are coronal consonants (made with the tip or front part of the tongue). However, there is a great deal of variety among sibilants as to tongue shape, point of contact on the tongue, and point of contact on the upper side of the mouth.
The following variables affect sibilant sound quality, and, along with their possible values, are ordered from sharpest (highest-pitched) to dullest (lowest-pitched): Tongue shape: grooved, alveolo-palatal, palato-alveolar, retroflex Place of articulation (point of contact on the upper side of the mouth): dental or denti-alveolar, alveolar, postalveolar, palatal Point of contact on the tongue: laminal "closed" (see below), laminal non-"closed", apical, subapical
Generally, the values of the different variables co-occur so as to produce an overall sharper or duller sound. For example, a laminal denti-alveolar grooved sibilant occurs in Polish, and a subapical palatal retroflex sibilant occurs in Toda.
Tongue shape The primary distinction among sibilants is the shape of the tongue. Because sibilants have such a high perceptual prominence, tongue shape is particularly important; small changes in tongue shape are easily audible and can be used to produce different speech sounds, even within a given language.
The following varieties of tongue shapes are defined, from sharpest and highest-pitched to dullest and lowest-pitched (see also ). Palatalization is an inherent part of the definitions of the varieties. Place of articulation Tongue shape Degree of palatalization Example in IPA Description Alveolar concave (grooved) none With a groove running down the centerline of the tongue. The groove channels a high-velocity jet of air into the teeth, which results in a high-pitched, piercing "hissing" sound. Because of the prominence of the sounds, they are the most common and most stable of sibilants cross-linguistically. They occur in English and are denoted with (as in soon) and z (as in zone). secondary (variable) Combination of grooved shape with palatalization (raising or bowing of the middle of the tongue). Palatalized alveolars often occur in the Slavic languages with a hard–soft contrast (such as Russian); they sound similar to the cluster occurring in the middle of the English phrase miss you. Denti-alveolar none Combination of grooved shape with dentalization (often referred to as "lisping"). Sibilants made with the tip (apical) or both the tip and blade (apicolaminal) of the tongue near the back of the upper teeth have a softer sound reminiscent of the English ⟨th⟩ sounds (as in think) and (as in this), though still with a distinct sibilant sharpness. Apicolaminals are typically denti-alveolar, while apicals approach true dental placement. These sounds are relatively uncommon, but occur for example in some dialects of Andalusian Spanish (where and lack a distinction and both merge to , a feature called ceceo), some of the indigenous languages of California, Acehnese, and Saanich. Alveolo-palatal narrow convex (peaked) strong With a convex, Ʌ-shaped (turned V) tongue, and highly palatalized. Such sounds are very rare in English (occurring only as occasional allophones in a few dialects), but characteristically occur for example in many varieties of Chinese, Russian, and Polish. Palato-alveolar broad convex (domed) moderate With a convex, "domed" tongue and moderately palatalized. Such sounds occur in English and are denoted with a variety of possible letters, including as in shin, machine, measure, vision, respectively. Sometimes referred to as "lamino-postalveolar" or "lamino-prepalatal". Retroflex flat (neutral) none With a mildly retracted tongue, neither curled nor palatalized, showing minimal concavity or convexity. Laminal retroflex sibilants do not retract as much as their apical and subapical counterparts (below), and are typically the most flat of all of the sibilants, though they may still approach a slight degree of doming. As such they are also sometimes referred to as "lamino-postalveolar" or "lamino-prepalatal", or if distinguished, "flat postalveolar". concave (curled) With a moderately concave, retracted tongue and no palatalization. Apical retroflex sibilants have less curling than their subapical counterparts (below), though still typically form a concavity. They tend to show some degree of velarization, and may approach a rhotic-like quality. Sometimes referred to as "apico-postalveolar" or "apico-prepalatal". With a strongly concave, curled back tongue and no palatalization. The subapical palatal (or "true retroflex") sibilants are the very dullest and lowest-pitched of all of the sibilants. Like their apical counterparts (above), they tend to show some degree of velarization, and may exhibit a near rhotic-like quality. Sometimes referred to as "subapical-postalveolar" or "subapical-prepalatal".
The alveolar sibilants are often labelled as hissing sounds, while the other types are often labelled as hushing sounds (sometimes referred to as shibilants because of their quality). Speaking non-technically, the retroflex consonant sounds somewhat like a mixture between the regular English of "ship" and a strong American "r"; while the alveolo-palatal consonant sounds somewhat like a mixture of English of "ship" and the in the middle of "miss you".
Place of articulation Sibilants can be made at any coronal articulation, i.e. the tongue can contact the upper side of the mouth anywhere from the upper teeth (dental) to the hard palate (palatal), with the in-between articulations being denti-alveolar, alveolar and postalveolar.
Point of contact on the tongue
The tongue can contact the upper side of the mouth with the very tip of the tongue (an apical articulation, e.g. ); with the surface just behind the tip, called the blade of the tongue (a laminal articulation, e.g. ); or with the underside of the tip (a subapical articulation). Apical and subapical articulations are always tongue-up, with the tip of the tongue above the teeth, while laminal articulations can be either tongue-up or tongue-down, with the tip of the tongue behind the lower teeth. This distinction is particularly important for retroflex sibilants, because all three varieties can occur, with noticeably different sound qualities.
For tongue-down laminal articulations, an additional distinction can be made depending on where exactly behind the lower teeth the tongue tip is placed. A little ways back from the lower teeth is a hollow area (or pit) in the lower surface of the mouth. When the tongue tip rests in this hollow area, there is an empty space below the tongue (a sublingual cavity), which results in a relatively duller sound. When the tip of the tongue rests against the lower teeth, there is no sublingual cavity, resulting in a sharper sound. Usually, the position of the tip of the tongue correlates with the grooved vs. hushing tongue shape so as to maximize the differences. However, the palato-alveolar sibilants in the Northwest Caucasian languages such as Ubykh are an exception. These sounds have the tongue tip resting directly against the lower teeth, which gives the sounds a quality that Catford describes as "hissing-hushing". Ladefoged and Maddieson term this a "closed laminal postalveolar" articulation, and transcribe them (following Catford) as , although this is not an IPA notation.
Symbols in the IPA
The following table shows the types of sibilant fricatives defined in the International Phonetic Alphabet:
+ IPA letters for sibilants Voiceless IPA Description Example Language Orthography IPA Meaning voiceless alveolar sibilant English sip "" voiceless alveolo-palatal sibilant Mandarin (xiǎo) "" voiceless palato-alveolar sibilant English shin "" voiceless retroflex sibilant Mandarin (Shànghǎi) "Shanghai" Voiced IPA Description Example Language Orthography IPA Meaning voiced alveolar sibilant English zip "" voiced alveolo-palatal sibilant Polish "" voiced palato-alveolar sibilant English vision "" voiced retroflex sibilant RussianPolish """"
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 "retracted sibilant" as , a transcription frequently used for the sharper-quality types of retroflex consonants (e.g. the laminal "flat" type and the "apico-alveolar" type). There is no diacritic to denote the laminal "closed" articulation of palato-alveolars in the Northwest Caucasian languages, but they are sometimes provisionally transcribed as .
Possible combinations The attested possibilities, with exemplar languages, are as follows. Note that the IPA diacritics are simplified; some articulations would require two diacritics to be fully specified, but only one is used in order to keep the results legible without the need for OpenType IPA fonts. Also, Ladefoged has resurrected an obsolete IPA symbol, the under dot, to indicate apical postalveolar (normally included in the category of retroflex consonants), and that notation is used here. (Note that the notations for is sometimes reversed; either may also be called 'retroflex' and written as simply .)