While some may think that standard-issue Ear2s are sufficient for detecting sounds that are too loud, the Hollins Communications Research Institute would have you believe otherwise, and for $50 they're willing to sell you a gadget that'll tell you when to turn down the volume or leave the room. A year in development, the Ear3 "Sonic Threat Indicator" uses specially calibrated electronics to warn you DHS-style of impending auditory doom, with a green light indicating a safe listening level, alternating green/red lights warning you to dial back the volume, a steady red light indicating possible hearing damage, and a flashing red light warning you that the tune you're listening to may be your last. It also apparently works equally well with headphones or earphones, although you'll have to keep taking them off and holding 'em up to the Ear3 every time you change the volume. Of course, you could get a pair of headphones that automatically constrain the volume
, or, you know, just turn the volume down.