The fight to build the world’s most powerful sound system:

Troy Irving’s 18-year-old Dodge Caravan has a heck of a sound system: 72 amplifiers — you got it, 72 — and 36 big 16-volt batteries to put out the 130,000 watts of power needed to rumble his nine 15-inch subwoofers… Must be fun to ride down Main Street with the windows rolled down, right?

Not really. At a curb weight of about 10,000 pounds, the Caravan is basically undrivable. There is virtually no room for a driver, and even less for a passenger… But he can at least sit in his driveway and listen to music, yes? Actually, no. Irving’s audio system can’t play music. It’s designed to play a single frequency — 74 Hz — very loud. Irving, you see, is a dB drag racer.

dB (as in decibel) drag racing is an obscure but growing international “sport” in which competitors go head-to-head for two or three seconds at a time — hence the name drag racing — to establish whose sound system is loudest. The 2002 record, set by a German team of secretive audio engineers, was 177.6 dB.

The roar of a 747 on takeoff is usually quantified at about 140 decibels, although there’s really no way to correlate the wide-spectrum noise of jet engines in open air with a low-frequency pure tone inside a highly reflective enclosure. Because the decibel scale is logarithmic, with every 10 dB increase equivalent to a doubling of perceived sound (otherwise known as noise), dB drag racing enthusiasts create some seriously loud tones. (Another rule of thumb: All else being equal, every three dB of increased sound from a typical dB drag racing system requires a doubling of amplifier power.) CNN