The book didn't go too much into the details of such "hearing" -- it focused more on having a constant chatter of messages that you could choose to "read" and respond to mentally, but very much like most people currently use facebook, IM, and e-mail. Video files and audio files were just part of the mix. Maybe this is a new trope in current sci-fi, this idea of internet in the brain. A book I read some time ago (not sure I could remember the title now) had a character going through a shopping center, and the store-fronts would target his "wetware" with low-range broadcasts, and he would have mental pop-ups of ads. All the things that we hate about the internet, forced into our heads, as we become more and more a slave to our need for connectivity.