[LAU] Linux programs for creatiing/manipulating sound effects

Folks, I've been thinking about playing with sound effects. For a lot of my life, i've been interested in the sounds that various things make and i am wondering if there is a linux program that would allow me to take a sound clip and manipulate it. Like taking the sound of a chair squeak and distort it, stretch it, apply filters to it, alter the tone etc. Is there a linux gui app for this sort of thing? Preferably in with the gtk tool kit as i have that all loaded up? I did some digging around, but i didn't see much. Of course there's always the chance that i looked at something that would do it well and didn't recognise it. What is that kind of program called? Thanks, Bearcat