As a father of two young kids who still use a sound machine to help them sleep, I was quite curious about a recent paper that warned that such devices may cause permanent hearing loss. Researchers compared a total of 65 sounds produced by 14 machines and measured the maximum sound level at a distance of 30 cm (crib-rail placement), 100 cm (beside crib placement), and 200 cm (across room placement). Why is placement important? When it comes to risk of hearing loss due to loud noise exp…