To understand the value of distinctive alarm signals, it is first necessary to understand exactly what they are and how they are being used to help more effectively keep people safe.
What They Are
Everyone has seen people with dogs that bark at everything. Eventually, those people seem to develop a sixth sense about the dogs barking. Sometimes, the owners will ignore the dogs and say, "It's nothing. They like to bark at cats at night." At other times, the owners will rush to the door to see what is going on because they recognize that there is a real problem that they should look into. It is not actually a sixth sense, it is simply that over time the owners have learned to differentiate different barks by their cadence and timbre. The bark in general is an alarm and the different tones warn owners of different situations.
Distinctive alarm signals are simply an extension of this concept. Instead of learning to judge subtle nuances in the sound, though, these alarm signals are designed specifically to stand out and be easily identifiable.
How They Keep People Safe
Different emergencies and level of emergency call for different responses. By building distinctive alarms into safety systems, people can not only be informed that there is a problem, but know from the alarm itself what the appropriate response to the signal should be.
Probably the most iconic and distinctive alarm in history was the cranked air raid siren used during World War II. This alarm was put in place because by the time someone saw a bomb, it was probably too late to do anything about it. The alarm was instituted to be sounded as soon as enemy bombers were sighted in the distance to give people as much time as possible to reach safe shelter.
In the modern world, electronic safety systems monitor different dangers and give alarms to let owners know which danger is present because the plan in each case may differ. For example, the response to a smoke detector may be a cautious exploration of the premises to find the source of the smoke. A heat or fire detector usually calls for immediate evacuation because by the time it is tripped, the fire has probably spread to a dangerous extent. Gas detectors universally call for an immediate evacuation because, like those bombs in the war, by the time a person actually sense them directly, it may be too late.
Distinctive alarms signals are crucial not only to keep people safe by alerting them to danger, but to allow them to tailor a response to the specific danger in question.