What Is Mpx

Recently, I have come across an audio file which ends with .mpX

What is .mpX and how do I play this file

.MPX

Microsoft Project export file (filename extension).

Source

I'm guessing this isn't what you mean though...try Google ;)

edit: could be this (RCA/Lyra Handheld MP3 Player File)

thanks for the reply. I have found out that by changing the extension from .mpx to .mp3, I can play the file in normal mp3 players