What term is used to describe marked use of sibilant sounds like s, z, sh, and zh?

The term that describes the marked use of sibilant sounds, such as s, z, sh, and zh, is sigmatism. This term refers specifically to the repetition of these hissing sounds within a given text, creating a specific auditory effect that can enhance the mood or tone of a literary piece. Sibilance can be particularly effective in poetry, drawing attention to certain phrases and contributing to the overall musicality of the piece.

Alliteration involves the repetition of the initial consonant sounds in a series of words, which does not specifically focus on the sibilant sounds. Assonance refers to the repetition of vowel sounds within nearby words, while consonance describes the repetition of consonant sounds at the end or middle of words. None of these terms capture the specific focus on sibilant sounds that sigmatism does.