Read 1 of these 2 files, or read them (and later, newer versions of GNU GPL) at http://www.fsf.org
LicenseOpenSource - GNU GPL 2 - granted for Audivolv, CodeSimian, Javassist3.9, WaveTree.txt
LicenseOpenSource - GNU GPL 3 - granted for Audivolv, CodeSimian, Javassist3.9, WaveTree.txt
Everything below this line is optional:

(Removed the optional CodeSimian Jar file in Audivolv0.1.5, but may add it again in a later version)

This file may help you understand those licenses: LicenseOpenSource Optional Summary.txt

The first line of every Audivolv source-code file should be: 
/** Ben F Rayfield offers Audivolv under GNU GPL version 2 or higher, in file LicenseOpenSource.txt */

The first 2 lines of every WaveTree source-code file should be:
/** Ben F Rayfield offers WaveTree under GNU LGPL any version, in file LicenseOpenSource.txt
The full name of WaveTree is "Immutable Sparse Wave Trees" */

All GNU LGPL softwares can be used as GNU GPL softwares. TODO check which versions that works for.
This is optional because it only grants you extra rights on top of the licenses above.

LicenseOpenSource - GNU LGPL 2.0 - granted for WaveTree.txt
LicenseOpenSource - GNU LGPL 2.1 - granted for Javassist3.9, WaveTree.txt
LicenseOpenSource - GNU LGPL 3.0 - granted for WaveTree.txt