Hard Wired For Sound: Love to hate your smoke alarm

20/01/12

With one in three battery operated smoke alarms failing in a house fire - most often because the battery has been removed - the Fire Kills campaign is reminding people that there's a very good reason why we all hate the sound of the smoke alarm.

Evolutionary instincts

We are evolutionally hard wired to notice changes in the sounds around us. In years gone by this natural instinct gave us early warning of approaching predators, but today it means that unusual sounds like a smoke alarm or siren will set off warning signals in our brains.

With a sounder pitched at the most sensitive range of the human hearing (3,000Hz), a triggered alarm will instantly grab the attention, while the persistent beeping means that we can't get used to the noise and tune it out as we do with many everyday sounds. Smoke alarms set at lower frequencies or set to vibrate and flash can produce the same effect for the hard of hearing.

All smoke alarms also have to be capable of waking an adult from deep sleep, which means they must sound at a minimum of 85 decibels from three metres away - that's comparable to the volume of a bus passing through your living room.

A matter of life and death

Never, ever remove the batteries in your alarm. It may be frustrating to find your fry-up has set it off again, but a working smoke alarm could mean the difference between life and death in a real house fire.

Volume

An average smoke alarm is required to sound at 85 decibels from a distance of three metres - it will be much louder at close range.

For more scientific information on smoke alarms, please visit the Hard-wired for sound section of the Communities and Local Government website.

Read more about why checking your smoke alarm weekly is so important, by visiting our Smoke Alarms Save Lives page.