The following links might be useful:

Online Converter:

CloudConvert:
https://www.digitaltrends.com/comput...to-mp3-format/

Software (free):

MediaHuman Audio Converter:
https://www.lifewire.com/free-audio-...ograms-2622863

I have not tried this one, but I have used other software from this company:

https://videoconverter.wondershare.c...converter.html

Audacity:

https://videoconverter.wondershare.c...-audacity.html

https://sourceforge.net/projects/audacity/