Hello I am an independent advisor for the Microsoft community. I found this file converter that should work on your files and change them to MP3: https://downloads.zdnet.com/product/2140-10494267/
Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.