How can I adjust the tone/noise of bell inside my home?

I had a Paragon Plus home alarm systems installed in my home in 1997. Unfortunately the electrician didn't furnished me with a manual. My problem is when setting the alarm at night when going to bed the noise of the bell is extremely loud and wakens the rest of the family.Unless we are all going to bed at the same time the alarm is not put on. Is it possible to get a manual to ascertain how I can adjust the noise level.I would appreicate hearing from you .Regards