Infant Sound Machines for Sleep May Cause Hearing Loss

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 exposure, there are three factors that come into play: 1) how loud is it; 2) how close is it; 3) how long are you exposed to it. Clearly, a person is at a higher risk for permanent hearing loss the louder a sound is, the closer the sound is, and the longer one is exposed to the loud sound.

When it comes to infant sound machines, two of the three risk factors are typically present given such machines are usually placed in or on the crib (close) and is typically played all night (duration).

Alarmingly, 3 machines produced sound levels 85+dBA which exceeds current occupational limits (if exposed for 8+ hours) for adults in the workplace which would mandate use of hearing protection. All 14 machines were capable of producing noise 50+dBA at distances of 30 and 100cm. 13 machines were capable of 50+dBA at 200 cm.

Which machines were tested? Beyond stating "procured from major online and brick-and-mortar infant-accessory stores," the machines were not identified. I wonder if the authors were fearful of lawsuits from sound machine manufacturers and as such, kept it anonymous.

Of course, one can always try contacting the ENT department at University of Toronto where this research was done and get an off-the-record answer.

Given lack of identification, the main steps a parent can take to minimize noise-induced hearing loss is to:

1) place sound machines as far away from infants as possible
2) set volume as low as possible
3) limit duration of sound machine usage


Reference:
Infant Sleep Machines and Hazardous Sound Pressure Levels. Published online March 3, 2014 (doi: 10.1542/peds.2013-3617)