You did say this, though:

>I think I can imagine sounds in my head, but it is a little like singing, or humming a tune without making noise.

This seems like how I and I assume most people experience the phenomenon of recalling or thinking about sound. It's just more or less vivid and detailed for different people.

Do you listen to music often? If so, you've never listened to a song and later had some sort of experience where something about that song stayed remnant in your mind?

If you try to imagine the loud alarm of an alarm clock, do you feel like you're experiencing something? By "experiencing", I mean you aren't just like "I can't even say any part of what I'm doing is imagining the sound of an alarm", but are in some way perceiving some kind of representation of some recollection of hearing an alarm clock's alarm.

Also, what happens in your mind when you hum something? To me, humming is the process of transforming that rough, vague, general "phantasic" representation of pitch/amplitude/time into rough, vague, general vocal cord movements. I could be very wrong, but I suspect that if someone is capable of humming anything with even the tiniest minuscule of correlation with the original song, then they don't have aphantasia (with respect to sound).

My speculative, uninformed hypothesis is that actual aphantasia is very rare and that sometimes there's misunderstanding of what it means, combined with the fact that some people have less vivid imaginations and mental representations than others.

Many people may have "weak phantasia", e.g. they may not internally imagine a 1-to-1 visual representation of what they saw on a walk on the previous day, or may not recreate every texture and pitch in a song they heard, but they can imagine some rough approximation of them. I think almost no one can construct these perfect mental recreations; maybe von Neumann and a tiny number of others.

For most people, I'd guess it's probably like 0.1 - 10%. But I think 0% is rare. And during dreaming, I imagine for most people it may increase to like 10 - 40%.

The weaker it is, I think the less one may feel attached to a term like "seeing" or "hearing". But I think no one is ever actually "seeing" or "hearing". It's just a mental representation which no term can fully describe. Kind of like how you can't exactly put a scientific, objective perceptual term to the experience of feeling love. It's just an internal, subjective experience within your mind. Something a little bit more like "reading" rather than "hearing", as you say.

And for internal monologue: if I ask you to "think" the phrase "I am going to go to the store", were you able to "think it"? If so, then I think you probably have internal monologue, or at least the capacity for internal monologue. It may not manifest very often, and you may "experience" it less "potently" than some other people, but I think you have it.

The suspected misunderstanding with internal monologue is that I think some people "spend more time with" their internal monologue than others. Like, a catastrophizer might regularly think the words "oh fuck oh fuck oh fuck what do I do", while for someone else their mind may be fairly "blank" most of the time, especially if they're distracted with something.

For people who experience it more frequently, some percentage of it may manifest and "bleed over" into spoken utterances, like the catastrophizer may sometimes mumble "oh fuck", perhaps without even realizing it. In my opinion, humming is often this same sort of "bleeding over" of the internal into the external, but with music instead of monologue.

Based on what you've said so far, I think you potentially might have visual aphantasia, but I think you likely don't have aural aphantasia or lack of internal monologue. And I think it's possible you also may not have visual aphantasia; there still might be a disconnect between what people mean by "visual imagination" and what you think they mean.