In June Mary Robinette Kowal did a livestream of her recording the audiobook of her new novel (out July 2020)
The Relentless MoonNot live now of course, but the entire session is on her Youtube channel.
The final book came in at 17 hours, the recording session is about 50 hours total.
She isn't an amateur "self-published" narrator, she has done several other authors' books.
https://www.youtube.com/playlist?list=PLBh-BXgsO9IjIJ3ITFYSP1JVAgjlGW-MvThe result is here, courtesy whackbag.
The Relentless Moon: Lady Astronaut, Book 3 - Mary Robinette Kowal
Listening to this book now, and she does some effects, like voices on intercoms. Had a look at the video to see how she did it: just partially muffled herself with a plastic cup. See
https://youtu.be/uKHixxpBvS0?t=6576 in Chapter 14 of the book, during lunar landing.