Popforge sound library is bundled with many sound processing and manipulation possibilities. The library is developed by Andre Michelle and Joa Ebert.
Please note that Flash example files are under trunk menu. One needs to download them as well as the whole core lib package. Below are links to the files.
http://code.google.com/p/popforge/downloads/list
http://code.google.com/p/popforge/source/browse/#svn/trunk/flash/PopforgeLibrary%3Fstate%3Dclosed
Happy soundings
Mti
There is a new audio engine by the makers of popforge here: http://blog.andre-michelle.com/2010/tonfall-open-source-audio-framework/