DB drag racing

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Properly spelled dB drag racing, with "dB" meaning decibels of sound pressure level (SPL). These competitions reward the person who can produce the loudest sound inside a vehicle.

SPLs of 155 dB levels are reached. A competitive vehicle might be a van weighing 10,000 pounds, with 72 (seventy two) amplifiers putting out 130,000 watts to nine sub-woofers (15 in.), powered by dozens of car batteries.

There were 10,000 competitors in 2003 and 300 "races". U.S. National Championships were held in Tennessee.

The vehicle must be driven 20 feet. Nobody is allowed to sit in the vehicle during trials because injury would be certain. The vehicles are sealed tight to maximize containment of the sound energy for the decibel level meter. The competitor stands away from the vehicle with an on/off switch control while a computer voice announces the stages for the "races". The test tone consists of a very short resonating tone between 30hz and 70hz, called "the burp".

The current loudest car of 2006 has been recorded at 178.9 dB. For comparison,

180 Rocket engine at 30 m; blue whale humming at 1 m
163 Windows break
150 Jet engine at 30 m
130 Threshold of pain; train horn at 10 m
120 Rock concert

The perceived loudness doubles with every 10dB increase, so 174.3 dB is about 5x as loud as a rock concert, and about 2.5x times as loud as a jet engine.

Sources

"This American Life" radio broadcast 2004-12-11 (["Auto Show"]).
[Extreme SPL Racing]
[CNN report]

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