I got this in a random lot with lot of pieces from 2001 sets. If you depress the black square on the side, it makes an auditory noise like a siren, but warbled, like in old sci-if movies. The body is white, except for the button, and the top is that radioactive orange that Lego doesn't make anymore. Also, only part stamp on it is H1. The lego stamp has no year.
It's a bb42 "Electric, Light & Sound Siren 4 x 2 x 4 Jack Stone"
and in that colour it came in the Police HQ set 4611 http://brickset.com/sets/4611-1