Science
12:37 pm
Thu September 5, 2013

Listen: 'Bending' Sound Makes It Difficult to Hear Firefighter Alarms

Virtually all firefighters rely on a simple device designed to alert their fellow firefighters when they need help.

It’s called a Personal Alert Safety System, or PASS.  It’s basically a sensor that measures whether the person wearing it is moving. If they're incapacitated or immobilized, the PASS sets off a 95 decibel alarm to draw the attention -- and assistance -- of other firefighters.

But there's a problem: In some circumstances, you can't hear the alarm. 

Take a listen:

Despite the PASS device's importance, up until just this year, there was actually no universal standard for what the PASS alarm should sound like. Different manufacturers had different alarms.

The idea with the new PASS standard is that no matter where you are, if you hear this one alarm sound, you’ll know a firefighter is in trouble.  Listen to the new, universal alarm signaling a firefighter’s in trouble: 

Click here to read and listen to KUT’s full story on the acoustics of fire.

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