What makes a good alarm?

Many current warning systems have several failings, and these failings demonstrate themselves admirably in many auditory warning systems currently in use including those often used on medical equipment. Twenty or thirty years ago the common consensus was that warnings should startle and alarm the operator in order to gain attention. For this reason alarms typically possessed many acoustic features which would cause these reactions, with the result that attention could be drawn away from, instead of towards, the problem in hand as well as raising the possibility that alarms might be turned off because of their aversiveness, then not to be reactivated in order to be ready for the next emergency. This view has now changed, and it is clear that in some environments, including the hospital environment in particular, that a design philosophy of this kind was always inappropriate. In this paper I will draw attention to some of the more recent developments in both warning design and warning philosophy in order to illustrate the criteria for a `good´ alarm, and how, specifically, such alarms can be designed