ACX will allow you to submit a 15 minute voice sample from a book. The sample must be fully Audiobook Submission and Publication Ready. As they comment, it doesn’t have to be fifteen minutes, but it should be long enough to give a reviewer a good idea what the rest of the book is going to sound like, and your mastery of file structure and editing.
ACX used to do this in days gone by, but stopped during the pandemic. They have ACX Labs on-line to help you, but ACX Labs checks the same things that Audacity ACX-Check does, but they don’t (last I Iooked) check noise.
Reading between the lines in the instructions, ACX tells you to pick a book from their list to read from. We assume this list is all the books for sale on Amazon. So you do have to be a published author in addition to all the other restrictions.
I believe they still won’t let you read a cookbook. My own personal idea is your target book should have Plot, Characters, and Setting.
Koz