Headphones "Tattle" if you crank the volume

Here comes a set of headphones that readily lets you know if your kids have raised the volume to an unsafe level (most likely this product will go over like a lead balloon with teens). The Guardian HA-31 headphones, by Hamilton Electronics, has red and green LEDs on the earcup. If you can't guess, red means "too loud".
Hamilton Electronics, a leader in electronics for the education market since 1933, is now introducing The Guardian Wired Headphone with SLM (Sound Level Monitor) technology. The Guardian has green and red LED lights so parents can visually monitor listening levels. A green light indicates a safe listening volume and a red light indicates that the sound is too high - alerting parents that the child may have a hearing problem or is at risk of causing irreversible damage to their ears.
That hadn't occurred to us - that if you note the sound level is too high, rather than just ratting out your kids, the Guardian might be letting you know the child's hearing is already impaired, rather than that he or she is damaging his hearing.