Judging from the running time of the audiobook version of The “Volunteer” as posted on the book’s Amazon and Audible pages, the corrected files have been loaded into production.  If you’ve already purchased the audio version, just go back to Amazon, Audible, or iTunes and re-download the book.  That should replace the uncorrected files with the new ones.  The book is, of course, also available in paperback and Kindle editions.

Audible: https://www.audible.com/pd/Erotica-Sexuality/The-Volunteer-Audiobook/B0785NJCZN

Amazon: https://www.amazon.com/The-Volunteer-A-Novel/dp/B077YR8NSY/

iTunes: https://itunes.apple.com/us/audiobook/the-volunteer-a-novel-unabridged/id1322630342