Digital Sound Editing Under Unix?

Jed1Mnd asks: "I have recently set out to find some decent audio manipulation software for Linux, with out that much luck. I have a friend who is currently using CoolEdit on Windows 98SE is running into issue with performance. We are looking at Linux because of the better IO, memory management and support for file systems like xfs. However like I said I am having trouble find a decent replacement for CoolEdit. I was hoping that the Slashdot crowd would know of a product (commercial or non-commercial) that would fit this situation."