Hearing your own voice Vs high fidelity musical instruments and other people's voices seems like a very wide spectrum. And indeed, it is wider as some people don't hear anything at all, including no inner monologue (I know someone like that - she's a good writer, and it freaks people out to realise the she can't 'hear' the words before she writes them, which is weird, because my vocalisation of words I wrote noticeably lags my writing)