Sound Device
Euphony
From Greek euphonia: sweetness of sound. Keats is the supreme practitioner; Tennyson exploited it for musical effect. The opposite of cacophony.
Definition
The use of harmonious, mellifluous combinations of sounds that please the ear and suggest beauty or calm.
Example
Tennyson: 'The moan of doves in immemorial elms, / And murmuring of innumerable bees.' (Princess)