Free public domain audiobooks
For a technical audience, I would look at some TTS (text to speech) programs especially by google and IBM.It's definitely robotic and nothing like a nice narrator but audiobooks are amazing regardless. And your mind actually starts filling in the emotional blanks. It can also be really cool to use like internet archive's scanned book's OCR -> TTS and make an audiobook from a cool old book that would never be professionally narratedAnd for anyone who listens to a lot of audio, I'd look into using an audio equalizer. Pulling down the high frequencies (especially for some woman narrators) makes it more comfortable after many hours of listening. On android the "Smart audiobook" app has this and it's really nice. Maybe some headphones/android phones can do this globally