"We have trailers with weapons of mass destruction chemical suits and medical equipment ready to haul, but we had no way to tow them," Lee said. For example, the medical examiner has a mobile morgue and trailers that would need to be towed by a heavy-duty vehicle. San Francisco purchased the trucks and equipped them with the Rumbler in case the need arose to haul equipment through city streets during a disaster. California agencies were free to use the Rumbler as of December 2007. Californians are just now getting a taste because of more stringent vehicle codes concerning light output and sound that had to be addressed. The Rumblers are being tested or used in a few cities across the country, including New York, Washington, D.C., and Elk Grove, Calif. The low-frequency tone can penetrate and shake solid materials, allowing anyone nearby to actually feel the sound waves and perhaps even witness their rearview mirror shake. It's not an overwhelming violent shaking, but a subtle feeling like a freight train kind of a rumbling."Īccording to manufacturer specifications, the Rumbler interacts with 100/200-watt siren amplifiers and provides a secondary, low-frequency tone. ![]() That alone gets attention, but then you will actually feel it. It mimics the tone but it's done at a much lower hertz level. "It just provides a contrast to the typical high-frequency siren. "It's an additional tool to combat distracted drivers, whether they have the stereo on, air conditioning, cell phones or general ambient noise," Sanchez said. The list price for the whole shebang is $685, according to Carlee Sanchez, senior district sales manager for Federal Signal. Now San Francisco has two 2008 Ford F-450s equipped with the Rumbler, which consists of a slave amplifier, a timer that's activated when the driver taps the horn, two speakers that operate like subwoofers and a mounting bracket. That day Lee knew the Rumbler would work as needed during a crisis. If it had been a regular siren, people would have pulled in front of me like, 'What do you want?' but everyone got out of the way." They were stopping to see what was going on. "Cross traffic was at a standstill as I went back to City Hall. ![]() "I'm watching people two and three blocks ahead of me, frozen with their hands covering their ears," Lee said. ![]() On went the siren, red and blue lights flashing, and then the unique feature of the Rumbler - the high-output speaker and subwoofers bounced low-frequency sound waves off buildings and vehicles. We haven't heard anything yet regarding the Rumbler's effect on vibration-sensitive car alarms, or backlash from neighborhoods roused from sleep by passing Rumbler vibrations.He tapped his horn, activating the Rumbler. Intended to penetrate solid objects (e.g., closed car windows or the chest cavity of a pedestrian) and overrun ambient noise-makers (car audio systems and iPods), or to physically get the attention of elderly drivers, the Rumbler does call to mind " brown noise," a semi-mythical ultra-low-frequency tone purportedly employed as a weapon during World War II (and as a modern-day crowd dispersant) that prompts the listener's anal sphincter to relax causing him or her to, um, lose control. As a traditional siren is heard, the Rumbler is felt. Fittingly dubbed The Rumbler, the siren (above right) consists of a pair of subwoofers that produce low-frequency tones complementary to the familiar high-pitched wail. ![]() Gaining momentum with police departments nationwide, including New York, Washington, and Chicago is a new kind of siren, one that promises to get the attention of even the most oblivious of motorists.
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