I don't know if this helps but you can do that in Adobe Audition (cool edit) and other similar recording softwares.
Not only that. You can edit wavs and mp3-files so much that I can say there is no any limits to it. You can even make surround sound with help of Adobe Audition (former Col Edit) and it is really easy to do that.
I use NERO and Nero Vision a lot but when it's a question of sound I do everything in Adobe Audition.