These are pictures of the speakers we are using to produce the alarm sound. The two speakers will be mounted on either side of the bat dropper and a battery powered amplifier will be attached to the back.

I've had them for a long time and while they don't sound great plugged into an music player, they are perfect for waking someone up. I simply had to strip the input wire and connect it in a circuit with a 10 k resistor to the pin associated with the speaker code and the speakers worked perfectly with Nick's code.