Rhyme, Alliteration, Assonance
Rhyme, alliteration, assonance and consonance are ways of creating repetitive patterns of sound. They may be used as an independent structural element in a poem, to reinforce rhythmic patterns, or as an ornamental element. They can also carry a meaning separate from the repetitive sound patterns created. For example, Chaucer used heavy alliteration to mock Old English verse and to paint a character as archaic.
Rhyme consists of identical ("hard-rhyme") or similar ("soft-rhyme") sounds placed at the ends of lines or at predictable locations within lines ("internal rhyme"). Languages vary in the richness of their rhyming structures; Italian, for example, has a rich rhyming structure permitting maintenance of a limited set of rhymes throughout a lengthy poem. The richness results from word endings that follow regular forms. English, with its irregular word endings adopted from other languages, is less rich in rhyme. The degree of richness of a language's rhyming structures plays a substantial role in determining what poetic forms are commonly used in that language.
Alliteration and assonance played a key role in structuring early Germanic, Norse and Old English forms of poetry. The alliterative patterns of early Germanic poetry interweave meter and alliteration as a key part of their structure, so that the metrical pattern determines when the listener expects instances of alliteration to occur. This can be compared to an ornamental use of alliteration in most Modern European poetry, where alliterative patterns are not formal or carried through full stanzas. Alliteration is particularly useful in languages with less rich rhyming structures. Assonance, where the use of similar vowel sounds within a word rather than similar sounds at the beginning or end of a word, was widely used in skaldic poetry, but goes back to the Homeric epic. Because verbs carry much of the pitch in the English language, assonance can loosely evoke the tonal elements of Chinese poetry and so is useful in translating Chinese poetry. Consonance occurs where a consonant sound is repeated throughout a sentence without putting the sound only at the front of a word. Consonance provokes a more subtle effect than alliteration and so is less useful as a structural element.