Sibilant sound

Sibilance is an acoustic characteristic of fricative and affricate consonants of higher amplitude and pitch, made by directing a stream of air with the tongue towards the sharp edge of the teeth, which are held close together; a consonant that uses sibilance may be called a sibilant. Examples of sibilants are the consonants at the beginning of the English words sip, zip, ship, chip, jump, and genre. The symbols in the International Phonetic Alphabet used to denote the sibilant sounds in these words are, respectively, [s] [z] [ʃ] [tʃ] [dʒ] [ʒ]. More specifically, the sounds [tʃ] [dʒ], as in chip and jump, are affricates, whereas the rest are fricatives. 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!").

In the alveolar hissing sibilants [s] and [z], the back of the tongue forms a narrow channel (is grooved) to focus the stream of air more intensely, resulting in a high pitch. With the hushing sibilants (occasionally termed shibilants), such as English [ʃ], [tʃ], [ʒ], and [dʒ], the tongue is flatter, and the resulting pitch lower.

A broader category is stridents, which include more fricatives such as uvulars than sibilants. Because all sibilants are also stridents, the terms are sometimes used interchangeably. However, the terms do not mean the same thing. The English stridents are /f, v, s, z, ʃ, ʒ, tʃ, dʒ/. Sibilants are a higher pitched subset of the stridents. The English sibilants are /s, z, ʃ, ʒ, tʃ, dʒ/. On the other hand, /f/ and /v/ are stridents, but not sibilants, because they are lower in pitch.

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