I use audible a lot. I've found that as I've got used to it I can increase the speed to around 2x. When I first started using it I usually set it around 1.25.

I use audible a lot. I've found that as I've got used to it I can increase the speed to around 2x. When I first started using it I usually set it around 1.25. It depends a bit on the narrator and the content. I find I often need to start with a new narrator at around 1.75 and then bump it up to 2 when I get more comfortable with their voice. But I would say that provided the speaker is clear and not heavily accented my language processing quite happily works at 2x speech speed. (Perhaps they deliberately speek slower for audio books though?). Whenever my wife hears it she says it sounds like nonsense to her, so I do think it's something that you get used to over time.