In relation to this comment in that article:
Of course the screamers need to be located such that they can't simply be disabled with one good whack from a hammer.
GP
That may be true, but a screeching alarm system (internal screamers, not the outside siren) is a deterrent because it means the burglar can't hear anything above the noise, which may attract someone's attention, and thus he would (or should) be concerned that someone might walk in on him without him hearing them coming.The screeching ones are like car alarms - no one listens to them or takes any notice because they just think it's malfunctioning.
Of course the screamers need to be located such that they can't simply be disabled with one good whack from a hammer.
GP