Your WAV file must have a: 16 bit or 24 bit (sample size), 44.1 kHz or 96Khz (sample rate), & a 1411 kbps (bit rate). 

MP3's can be converted to a WAV file using a 3rd party conversion website such as https://convertio.co/mp3-wav/ or a free audio editor like Audacity

To convert your file to the proper format in Audacity:

Download/Install
Open Audacity
File - Import - Audio
Select the file you want to import.
Once the file is loaded, File - Export - Export as WAV
Change the file type to "WAV signed 16-bit PCM" or "WAV signed 24-bit PCM"
Click "Save"
A Window will pop up to "Edit Metadata Tags" click Cancel

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