I think it might be by Ray Bradbury.
Music has been reduced to clips from jingles/commercials. There's a machine that writes the songs, but protagonist goes to work in small club/bar & becomes very successful.
He picked up the Com lyric again, and his mind began to shape the thread of a melody.
“If your flyer jerks and clowns, if it has its ups and downs, ups and downs, ups and downs, you need a WARING!”
He hummed softly to himself, sketching a musical line that swooped and jerked like an erratic flyer. Word painting, it was called, back when words and tones meant something. Back when the B-A-C-H Baque was underscoring such grandiose concepts as heaven and hell.
Baque cleared a corner for himself and sat down wearily, stretching his long legs out under the table.
“Damn Hulsey,” he muttered. “Damn sponsors. Damn visiscope. Damn Corns.”
Compose something. You’re not a hack, like the other tunesmiths. You don’t punch your melodies out on a harmonizer’s keyboard and let a machine harmonize them for you. You’re a musician, not a melody monger. Write some music. Write a — a sonata, for multichord. Take the time now, and compose something.
Found by searching this site for
[story-identification] jingles which returned, among others, Short story about advertising replacing music