I don't know if the researchers at SLAC National Accelerator Laboratory, based at Standford University, happen to be metalheads, but as far as I am concerned, they are at the very least, honorary headbangers.
The team has produced “record-shattering underwater sound with an intensity that eclipses that of a rocket launch,” using the “Linac Coherent Light Source (LCLS).” They basically send an x-ray laser to blast tiny jets of water with short pulses of high frequency energy. The jolt instantly vaproized the water molecules around them.
Cnet breaks it down that the sound pressure is the equivalent of 270 decibels, which is "louder than a rocket launch and equal to the intensity of directing all the electrical power in an entire city onto one spot."
Even ear plugs wouldn't help you if you were to experience such a sound directly, as the intensity wouldn't only rupture your eardrums, but also your heart and lungs as well.
Sleep and High on Fire guitarist Matt Pike is on the phone with his amp company right now to figure out how to get his cabs to 270 decibels.