Vox Imperium: Stormtrooper Voice Changer
To start, solder headers onto the Teensy and Prop Shield. You'll also want to solder female headers to the edge pins on the Teensy, the edge pins on the Prop Shield, and the Prop Shield's audio out port.
Cut and strip six lengths of wire, each about 6 inches long. Solder them to the speakers (note that you'll need to splice two wires to one for each positive and negative terminal).
Fritzing Wire Diagram
Connect the components as shown in the breadboard. Follow the wires if you plan to put this into a helmet.