Try 5-6x. I've met some blind people who listen to audio so fast, it sounds like noise to me. As someone who isn't blind, I regularly listen to lectures and audiobooks on 1.75-2.5x (depending on the base rate) without issues, but 6x is just something else entirely.
> Typos will be easily spotted as they just won't "sound right".
Really good way to describe this. It's almost like listening to an audio fingerprint which magically indexes the answer in your brain. My blind friend was doing law, but I'm sure she did something similar to help her map the dependencies between laws.