If you are meaning mp3 to wav, yes, but very few are free, and most are trial version with limitations of like 15 conversions, then option to buy.
But yes they are out there.
Check these sites, and see if you find what you want, you may have to do some searching........
Once you find what you want, Windows comes with a utility called Sound Recorder.
You will find it in the Entertainment area, of you Accessories menu.
It can split wav files into pieces, combine, change speed, add echos, and convert the properties of the file, so it takes less space on your maps.
Always keep in mind the dialup users of the game.
The more sound files you add, the slower the download for them, or anybody that downloads from them.
Less is More