A Rumbler siren is a type of emergency vehicle siren used primarily in the United States and Canada.
Developed in 2007 by Federal Signal Corporation, and sounding at a low-frequency level, it is designed to be heard by motorists who may otherwise be unable to hear high-frequency sirens due to ambient noise, such as urban traffic.
The Rumbler produces a pulsating, low-frequency sound between 182 and 400 hertz, [1] and is operated in tandem with a standard, piercing high-frequency siren. The lower frequency sound penetrates hard surfaces like glass and doors more effectively than high-frequency tones. In addition, the siren's low-frequency thumping sound also causes noticeable vibrations to drivers and pedestrians who are near it and helps to generate attention in high-noise environments like dense urban traffic. The Rumbler is about 10 decibels quieter than a standard emergency vehicle siren and is generally activated in eight-second bursts by depressing the horn button in a Rumbler-equipped vehicle. [2] [3] [4]
The Rumbler was developed by Federal Signal Corporation as an "intersection clearing device". It was initially tested by the New York Police Department in 2007. [3]
According to Noise Off, a noise pollution advocacy group, more than 100 U.S. police departments had deployed the siren by 2012, including those of: Washington, D.C.; Amarillo, Texas; Tulsa, Oklahoma; and Reading, Pennsylvania. As of 2016, the per-unit cost of the siren was between US$400 and $700 (equivalent to between US$524 and $917 in 2024). [5] [3] [6]
In 2015, emergency vehicles in New South Wales, Australia, were outfitted with Rumbler sirens and, the following year, some ambulances in Singapore began to be equipped with the Rumbler. [7] [8] According to Singapore officials, the decision to adopt the Rumbler came after seeing its efficacy in U.S. police vehicles. [7] [8]
Wales Air Ambulance's response vehicles are now equipped with the rumbler siren. [9] This is the second application of such equipment in the UK, having only previously been used by another response doctor charity in Hampshire. [10] In 2023, more UK police services began to have their cars outfitted with Rumbler sirens, as the siren's low frequency produces a tactile effect that allows drivers to be clearly alerted to the siren's presence, even in modern cars with extensive soundproofing which would otherwise block out most of the sound. [11]
"Rumbler" was a nominee for "People's Choice Award Word of the Year" for 2016 by the Macquarie Dictionary . [12]
New vehicles operated by the Queensland Ambulance Service are fitted with a Rumbler siren.
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