Sibilance is used as a stylistic device in poetry in which an "s" sound is repeated more than twice in quick succession. Sibilance is a specific type of alliteration that uses the soft consonant sounds "s," "sh," "ch," "th," "z," "x" and "c." These consonants produce hissing sounds. The "s" sound is most often used as a sibilant.
When using a sibilant, the sound is made by using the tongue to direct a stream of air towards the sharp edge of the teeth, which are held closely together. A sibilant does not have to be at the beginning of a word.
Sibilants are usually an intense sound, which is why they are often used to attract people's attention, such as saying "Psst!" to call someone or saying "Shhh!" to admonish someone to be quiet. Poets use sibilance to create an atmosphere within a poem, and to have a musical effect on the readers. The repetition of one set of similar sounds draws the audience's attention to words with those sounds.
Words with a sibilant include "sip," "zip," "ship," "chip" and "vision," which has it in the second consonant. An example of using sibilance in poetry is, "I must go down to the seas again, to the lonely sea and the sky, / And all I ask is a tall ship and a star to steer her by" from the poem "Sea Fever" by John Masefield.