Dissonance in poetry is the deliberate avoidance of assonance, i.e. patterns of repeated vowel sounds.
[n] disagreeable sounds
[n] the auditory experience of sound that lacks musical quality; sound that is a disagreeable auditory experience; "modern music is just noise to me"
[n] a conflict of people's opinions or actions or characters
antagonism, argumentation, atonalism, atonality, cacophony, clashing, clinker, conflict, contention, contradiction, contrariety, contrast, controversy, departure, deviation, difference, disaccord, disaccordance, disagreement, disconformity, discongruity,