Poetry set to music, song.
When skilled men write for music, then music can both render their movement, as Lawes does often, tone by tone, and quantity by quantity; or the musician may apparently change the word-movement with a change that it were better to call a realisation. Music is not speech. Arts attract us because they are different from reality; yet differ in some way that is proportionate to reality. Emotions shown in actual speech poured out under emotion will not all go into verse. The printed page does not transmit them, nor will musical notation record them phonographically; but for all that, a certain bending of words or of syllables over several notes may give an emotional equivalent.
--EP Ezra Pound and Music, ed. R. Murray Schafer, New Directions, pg. 86.