For sound-effects I'd recommend "audacity", which needs "lame.dll" as file for converting your file into mp3-types, which isn't included in the downloadversion so far. Still I like the slow/speed-up effect with optional echo and cutting out specific parts, inserting them in the same or additional audio-line within the same project. Maybe depends on the version of app you're using, I'm preferring an older one which includes those features.