Volume-Limiting Headphones

Sounds louder than 85 decibels can cause hearing loss, but most digital music players can exceed that threshold. Headphones and ear buds from iHearSafe of ­Milford, NH, have a volume-­limiting circuit hardwired into the cord. Unlike the software that some concerned parents have used to cap the volume of their kids’ music players, the hardwired circuit can’t be digitally circumvented.

Credit: Joshua Scott