Why do uploaded voice recordings to my PC save as WAV files?

I thought this was an MP3 player.  Wouldn’t the default file type be MP3?  When I upload, the file saved to my PC is WAV, so I have to convert it to MP3.  Is there any way to avoid this?

Thanks everyone!

the express will plave wav files as well no need to convert.

The default recording format fo sansa is only in wav format, its a pity, that you cant chose the format and bitrate