There is a brief discussion on 'musical hear hallucinations' in the Mental Health Forum on MCC. https://connect.mayoclinic.org/discussion/auditory-hallucinations-and-musical-ear/
That discussion is addressing it from a mental health perspective.

However, 'musical ear' is a very common thing among people who have hearing loss. It's a mystery. In my case, I can hear a variety of music from past years when my hearing was much better than it is now. All those songs, many of which I can bring up at will are songs from 30+ years ago. It's actually quite pleasant until it becomes repetitive. In most cases, I can change the song by thinking of something else similar in tempo.

A few days ago the song "Hey Look Me Over" kept playing and playing. It's a positive song, but anything that gets repetitive is annoying. I didn't know what musical it was from, so looked it up online. It's from 'Wildcat' staring Lucille Ball. I have no recollection of that musical from the early 60s. However, it was sung by several other artists then. Looking at the lyrics amazed me as I remembered every word of that song perfectly.

The ear is an amazing gateway to the brain. Until the late 1980s most people who started losing hearing were told that nothing could be done to help them because the auditory nerve, which sends sound to the brain for interpretation was dead or dying. People were given no hope of hearing help back then.

The concept of cochlear implants was scoffed at by the ENT profession, except for a few researchers who dedicated themselves to their belief that it was the cochlea (inner ear) that was faulty in sending singles to the auditory nerve to send to the brain. Thankfully, a few test subjects agreed to be involved in experimental surgery. The main discovery was learning that the auditory nerve was not dead or dying, but the cochlea was. Today, cochlear implants are able to bypass the natural organ and stimulate that nerve for the brain. Pretty amazing stuff. Still no answers to that musical ear syndrome, but most people seem able to control it.

bobbyjo21, you say you have hearing loss. Do you use hearing instruments?