Why is Low Frequency So Important?

Stu Tisdale

By
On March 4th In Fire
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We’ve been trained to evacuate a building when emergency alert horns and horn strobes sound during a fire event. Ideally you would respond as soon as you hear the audible device, but what happens if you’re sleeping and unable to react right away? What if you’re hard-of-hearing?

Studies conducted by the National Fire Protection Association, (NFPA) 72 committee and the FRPF found that many high-risk groups had a delayed response when audible devices went into alarm, and that certain high-risk groups had a delayed response to the 3 Kilo-hertz tone found in many smoke alarms and audible devices in the US market. High-risk groups, such as individuals with mild to severe hearing loss or those under the influence of sleeping aids or alcohol, had a delayed response with higher frequency tones.

Studies found that audible devices with a square wave tone with a lower frequency, 520 Hz, were more effective at waking sleeping individuals. The devices were even effective at waking those with mild to severe-hearing loss or people under the influence of alcohol or sleeping aids.

The latest editions of NFPA 72 and 720 now require audible devices connected to a protected premise fire alarm system to produce their alarm tone at 520Hz and square wave tone when installed in sleeping spaces.

ADI Global Distribution offers a wide range of low frequency products for your installation needs, including solutions from System Sensor. Choose from low frequency sounders, sounder strobes and sounder bases.

Click here to watch a webinar hosted by System Sensor to learn more about the low frequency requirements and applications.

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