Recent mentions of The Hitchhiker's Guide to the Galaxy in the comments have prompted me to talk about this: an adult friend and I used to read books aloud to each other. Reading aloud isn't just for children's stories.
We started doing this when, as a Christmas gift, I gave her the “Hitchhiker's Guide” trilogy, and one day in January, when we were otherwise idle, I just picked up the first book and started reading it. After that, we read many books to each other over the years, with neither of us doing it all, but loosely taking it in turns. “Loosely”, because we'd skip a turn if the situation warranted; for instance, she couldn't read in a moving car and I could, so we made sure it was my “turn” to read when we had a car trip coming, and she'd drive while I read. It made the drive seem so much shorter.
It also wasn't so much one of us reading “to the other”, as it was one of us reading “to us”. Except for the “Hitchhiker's Guide” series, we chose books that neither of us had read before, and so the books were new experiences for us both, and the reader, as well as the listener, was seeing it for the first time. This does add some challenge for the reader, since the material is unfamiliar. We both tried to use intonation appropriate to what was being read, and I, in particular, good with voices, liked to put different voices and accents to the different characters. Cohen would get a New York Jewish accent, O'Rourke would have a bit of an Irish brogue, and so on. But many was the time I'd have Cohen and Shapiro arguing in their way, and O'Rourke would intercede with, “Vill you shtop yellink, you'll vake the dead!” Oops. Begorrah. Or I'd shout, “Oh, just leave me alone!, ” Um. “...she said quietly as she left the room.”
Perhaps the most interesting challenge is reading things with adult vocabularies. We often don't realize how we take words for granted when we read them silently, but when we read aloud, especially when we do it with adult, not children's material, we encounter many words that we know very well... but that we've never said aloud before. This often lead to the “Is that how you pronounce it?” interruption as we'd look the word up in a dictionary. Sometimes I was right. Sometimes my friend was right. Sometimes we were both right, with a word that has more than one acceptable pronunciation. Sometimes, though rarely, we'd find we were both wrong. And once in a while the one of us who was wrong would refuse to accept the verdict of The Dictionary, and would continue to pronounce the word wrong, thank you very much.
It does take longer to read a book this way; with limited time available, Michener or Eco can take months to finish. And it's not something we could do, say, on a plane flight. But it is such a delightful way to read a book.