Texas Fire Chief - Spring/Summer 2008 - (Page 33)

Alarms for the Hearing Impaired A STUDY CONDUCTED BY THE FIRE PROTECTION RESEARCH FOUNDATION A ugust 2, 2007: According to the July 2007 study, “Waking Effectiveness of Alarms for Adults who are Hard of Hearing,” the typical audible signal used by smoke alarms failed to wake up 43 percent of tested subjects with mild to moderately severe hearing loss despite the fact that all were able to hear the 3100 Hz tone when awake. Strobe lights woke up only 27 percent of the hard of hearing subjects. In contrast, a specific audible multiple frequency signal consisting of a 520 Hz square wave successfully alerted 92 percent of the subjects at the benchmark level of 75 dBA and alerted 100 percent at 95 dBA. The study, authored by Dorothy Bruck and Ian Thomas of Victoria University, Australia, estimated at least 34.5 million people in the United States have partial hearing loss and projected that this number would increase due to the aging of the baby boomer generation. The Hearing Loss Association of America (HLAA) has long suspected that people have died in fi res because they could not hear or wake up to high-frequency smoke alarms, but government investigations of fi re fatalities have not inquired into whether the victims had hearing loss. Neither audible smoke alarms nor strobe lights were specifically tested with hard of hearing people during stages of deep sleep until the twenty-fi rst century. The fi ndings of this study indicate that millions of people with hearing loss will not be wakened from deep sleep by audible alerts which use only one tone in the high frequencies rather than a range of frequencies beginning at approximately 500 Hz. “This study shows there is a critical need for emergency warning systems to be redesigned or supplemented as soon as technically feasible,” said Terry Portis, executive director of the Hearing Loss Association of America. “Millions of people do not and will not know that they will not wake up to the high-pitched tones used by most emergency alerts. We call upon manufacturers of emergency alerting equipment, such as smoke alarms, carbon monoxide alarms and weather radios, to provide solutions that recognize this reality as soon as possible.” The study evaluated the performance of six different signals for waking up hard of hearing people from deep sleep and found the 520 Hz square wave to be the most effective of all the signals. Bed and pillow shakers awoke 80 percent of the subjects at benchmark levels, awaking the majority very quickly, but did not wake up 100 percent of the subjects even at higher levels of intensity. For people with more severe hearing loss, the authors recommended studying the effectiveness of two or more different signals, such as a 520 Hz square wave audible signal with a tactile alert and/or a strobe light. “Even though strobe lights may not be effective by themselves at waking up hard of hearing people from deep sleep, it’s important to remember that strobe lights are still needed for alerting deaf people when they are awake and are not 33 TEXAS FIRE CHIEF Spring/Summer 2008

Table of Contents Feed for the Digital Edition of Texas Fire Chief - Spring/Summer 2008

Texas Fire Chief - Spring/Summer 2008 Contents Executive Director’s Report Region Realignment Map Above and Beyond 2007 Conference Highlights ‘Service Above Self’ Texas Commission Implements Southwest Fire Rescue Conference Program Membership Application Who Are Those Guys? Alarms for the Hearing Impaired Recent Calls Index to Advertisers

Texas Fire Chief - Spring/Summer 2008

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