I call this stuff "brain noise" and the people treating me seem to know what I'm talking about which makes me assume it is fairly common. I have hyperacuity anyway so I jump and respond to all sorts of sounds (today my therapist's water bottle made a crinkle noise and I jumped and he said I was also responding to traffic; he monitors this because if I start doing it a lot I'm getting manic). But brain noise is different than that and it's different than any time I've heard voices or been paranoid. I think it's just the brain trying to keep up with itself or something like that, sort of like a record skipping while the brain (the record) is trying to get a coherent thought out.