Soften Siren Chirp?

I just installed a Crimestopper CS-2001RS, great unit, no hassles with the install, sick range! My only problem is the siren chrip... sounds a little bit like Smokey's mom's Pinto in the movie Friday. I'd like to soften up the chirp quite a bit. Any ideas of how to do this without affecting the siren output (which is pretty damn loud!). I know I can get another siren but I'm on the cheap here.

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Do you want to change the tone/sound or just the volume? If just a volume change, then you'll just need a resistor. Make sure you measure the current going into the siren first. The siren's output will probably vary logarithmically with the current through it; i.e. if you drop the current by 10%, the output will drop by half. So calculate the current you want based on the volume decrease you're after, and use a resistor to reduce the voltage drop across the siren... THE BELOW IS ONLY A 1st-ORDER CALCULATION! Say your siren draws 1A, for ease in calculation. If you want 50% output, you'll want 0.9A or 900mA. To get 900mA, you'll want 90% of the existing voltage drop. 90% of 12V is 10.8V. So at 900mA, you'll want the resistor to drop 1.2V. So V=IR or R=1.3Ohms. Keep in mind that at 1.3 ohms and 900mA the power dissipated by the resistor is 1.17 watts. So don't go sticking a little 1/4-watt resistor from radio shack in there! You'll probably want two 1-ohm resistors in series, and you'll want at LEAST 1-watt resistors. I would go with two 1-ohm, 2-watt resistors in series. Of course, this gets very interesting if the siren draws different amounts of current at different frequencies! I won't even go there... DDR

Thanks for the info guys, what I was looking for was something to soften the chirps, not the siren output. It came to me while I was in the gym, use resistors for one feed of the siren, then use a relay with a resistor and cap to switch on after 1 second to give full siren output.