I can't visualize and I can't hear anything in my head. I can think in words, I just can't hear them. When I'm thinking about what to say I think of the words as I contemplate the wording, but they go away fast and I never hear them. Sometimes I'll feel my mouth or lips preparing to move, as if I'm about to say the words, but I don't actually move them. If I'm thinking about an argument I just had or something, I'll think about what I could have said, but not actually hear anything. I don't normally think about what the other person would say word-by-word, but just as a concept.
I'm in my late 50's, and I never knew either visualizing or actually hearing things was actually a thing people could do, let alone that the vast majority of people could do them until hearing about aphantasia. The thing is, I know things are happening in other areas of my brain. I will start thinking about a problem that I need to solve, programming or otherwise, and at some point I'll go away for a while and come back to awareness knowing that the other part of my brain is still working on it. Sometime down the road, the answer will pop into my head. When I'm reading I will start thinking word by word, but after a while I'll realize I'd been reading for a while now without thinking of the words or hearing anything, but still knowing what was going on. When I'm thinking about code, I can usually figure out that the problem is partway down this particular file, after some initializations and before the blah blah blah function.
I still get earworms, though. I just can't hear them. It's like someone is playing the music loud down the hall through a closed door. I can tell what it is, but I can't really hear it.