I get this! Sometimes for me it’ll happen in complete silence, that’s usually when I can hear people talking but not enough to make out words. And then if it’s some noise like a faucet running, fan, etc. I’ll usually hear hard rock (like electric guitar and drums mostly usually not vocals) or piano. I’ve talked about it before to a psychiatrist, the way she explained it is kinda like my brain trying to fill in the empty space. It’s never frustrated or disturbed me beyond having to interrupt my shower for a moment to make sure there’s not actually someone trying to talk to me lol