I have aphantasia, and I also remember songs in multiple parts vividly. I won't go so far as to say it's eichoic--I can't, for example, turn around and just play a version of it on piano like some people I know, and I'm fairly sure I'm recalling an approximation in a lot of cases--but it's a detailed enough recollection I can "listen" to songs that way by recalling them. It's very much in contrast to my non-existent ability to recall even a familiar image.
I've considered cause/effect on this before and personally just decided it was probably coincidence combined with my poor visual memory making the other types seem that much more impressive. There's no particular compensatory mechanism I can think of that would explain remembering sound better because I remember vision worse.
Interestingly, I've never been any better at composition (i.e., imagining novel music) because of this. To the extent I've composed, I still pick stuff out a part at a time and figure out how it fits rather than starting with a finished sound in my head to recreate.
I view things like perfect pitch as distinct from a strong musical recollection. With effort, I can transcribe music and eventually learn it, but it's a separate skill in my mind.
The ability to "listen" to songs by recalling them is more what I was referring to when discussing my experiences. I'm with you on the non-existent ability to recall imagery.
I have no idea if there is some type of connection between the two, but it's interesting that at least two of us seem to have similar experiences!
I've considered cause/effect on this before and personally just decided it was probably coincidence combined with my poor visual memory making the other types seem that much more impressive. There's no particular compensatory mechanism I can think of that would explain remembering sound better because I remember vision worse.
Interestingly, I've never been any better at composition (i.e., imagining novel music) because of this. To the extent I've composed, I still pick stuff out a part at a time and figure out how it fits rather than starting with a finished sound in my head to recreate.