Earworms & musical tracks
A common dissociative experience for many plurals is intrusive earworm experiences. This is the experience of "having a song stuck in your head" and can include snippets on repeat, continual soundtracks that play all day & night, other sounds or noises that are constant, internal sounds that attempt to drown out the perception of audio input from external sources, etc.
While having an earworm is not exclusive to plurals, most singular folk who experience this issue have it occasionally where many plurals have this issue constantly or at least frequently. It's important to note it's not anything like a diagnostic criteria. It's probably a "normal" or "commonplace" dissociative experience that, being highly dissociative, plurals & multiples experience far more frequently (even constantly) than the average person.
The music — perhaps "soundtrack" is more accurate — can be published works, repetitive noises or filler tracks, or can be original tunes, altered lyrics of standard songs, etc. Some plurals have more than one earworm at the same time.
Some folk call it a "radio in their head" experience.
Earworms may also be accompanied by other headmates ramblings (like talk radio) that intrude on the inner shared or fronting experience but are not actually having a 2-way interaction or conversation.
Some plurals find it helpful to play a song that gets stuck on repeat. It may be as if the "person" who is playing the music got stuck and needs to hear the original song again to get past where they're caught up.
Other plurals don't find external music helps any, the internal song continues in spite of it, which may be disturbing, or the songs may be out of sync.