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 puting out 130,000 watts to nine sub-woofers (15 in.), powered by dozens of car batteries.

There were 10,000 competitors in 2003, 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. Computer voice announces the stages for the "races". The test tone consists of a three second 74 Hz tone, called "the burp".

Sources

• "This American Life" radio broadcast 2004-12-11.
• Extreme SPL Racing
• CNN report

The current loudest car of 2005 has been recorded at 174.3dB