A Sound Off on Tone


editorialBy Roopa Shortt,
Audible Visible Marketing Manager, System Sensor

Through our work developing products and meeting intelligibility code requirements with our audible life safety systems, we’ve long realized an important point: Proper notification isn’t just about turning up the sound. It’s about being heard – and understood.

For many people the tones in most smoke alarms are outside of their reasonable hearing range. Whether it’s due to hearing loss, age, health issues or other impairments, there are millions of people who have difficulty hearing the higher frequency pitches that are common in today’s audible devices.

This becomes an even more serious problem when these individuals are asleep. As a result, NFPA 72: 2010 and 2013 now require using a 520 Hz square wave signal in devices protecting many sleeping areas, including commercial sleeping spaces, by January 1, 2014.

Wayne Moore, principal and vice president of Hughes Associates, explains in this issue’s Ask the Expert column that specifying a 520 Hz signal for voice communications systems is an obvious choice for at least two reasons: First, it encompasses universal design because nearly everyone can hear it. Research has found that audible emergency evacuation signals set at a 520 Hz square wave tone successfully awakened 92 percent of hard-of-hearing test participants when used at or below 75 decibels. Second, 520 Hz improves awakening rates for other populations.

System Sensor has made meeting this new requirement easier with SpectrAlert® Advance Low Frequency Sounders and Sounder Strobes, the first notification appliances to meet NFPA’s low-frequency requirements for sleeping spaces. These devices easily integrate into the panel’s notification appliance circuit line and include many features that increase application versatility and simplify installation.

We’re proud to offer systems that improve life safety protection for everyone.

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