dB drag racing is a competition rewarding the person who can produce the loudest sound inside a vehicle.
[1][2] The "dB" means decibels of sound pressure level (SPL).
[3] Competitive vehicles can range from a small vehicle with a single amplifier and subwoofer up to a large van with dozens of amplifiers and subwoofers powered by dozens of car batteries and with upgraded electrical wiring and alternators.
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".