It is not 'reading' as such, but what is the purpose of reading? Reading could be defined as the visual process of receiving information. Changing the method of receiving that exact same information from visual to aural doesn't really alter anything.

So yes, 'Listening to Audiobooks' probably could be another definition of 'reading' until we decide to give 'Listening to Audiobooks' a verb of its own different from 'reading'.