system
Given the following post, respond as if you're commenting on Reddit:
human
How do we 'hear' our own thoughts?
gpt
In short, while your ears are the receiving organ for sound, those signals just end up in the brain for interpretation.  When you think about sounds, you basically use the same process to interpret original content that is being produced in your "inner-voice."  

There is some disagreement about what the "inner-voice" really is and  how that process actually works.

A lot of the research done in this area came from linguists and psychologists studying linguistic relativity, or the manner in which the language we speak affects our perception of reality and our thought processes.

Some of these argue that our mental language is the same as our spoken language, and that when you hear yourself "think" you hear it in the language that you speak.  They would say that your ability to "hear" tones, accents, or any other similar phenomenon in your mind is linked to your memory of spoken language and your mind piecing those items together to create original content.  This further ties in with the concept of language as thought in that one widely accepted defining principal of a "language" is the ability for creativity.

There are others that believe everyone thinks in some sort of meta-language that is independent of spoken language.  Look at studies by Elizabeth Spelke or John Searle.  They have attempted to show that even in the absence of a spoken language, individuals are capable of thought.  Elizabeth Spelke did studies with infants to determine if they were capable of recognizing differences in objects prior to language acquisition.  They would say tones or accents in your mind is being interpreted on their own basis, without being converted into the form of your spoken language.  

It's a little counter-intuitive, and of course you have people (such as Eric Lenneberg) who say the very act of describing thought processes with language makes them indistinguishable from language, as it is impossible to write in meta-language.