Assonance

Def:
is the repetition or a pattern of similar vowel sounds.
Examples:

The Bells
by
Edgar Allan Poe

Hear the mellow wedding bells,
Golden bells!
What a world of happiness their harmony foretells!
Through the balmy air of night
How they ring out their delight!
From the molten-golden notes,
And an in tune,
What a liquid ditty floats

Sign:

It makes the sounds more creative, like making music in poems, attractive to readers.