I must say this truly depends. I can sometimes be more focused with an audiobook. An extreme example? Heidegger's Being and Time, Macquarie and Robinson translation. The audiobook version read by Martyn Swain is a godsend for helping one try to grapple with this monster. Though his only commentary is in timbre, rhythm, speed, it absolutely enriches the reading. The audiobook is something like 24 hours long, but there's just no way you finish in that time (if you ever do finish); if you're like me you've gotta rewind rewind rewind, baby.

A talented reader can work magic. Ukemi and Naxos have great titles.