Hazardous sound outputs of white noise devices intended for infants.
Level 5 - mechanism / opinion, no new human data
Bench/device testing with no human subjects; clinical CEBM level 5 by design analogy
PubMed 33992973 · doi:10.1016/j.ijporl.2021.110757
What was done
Sound intensity in A-weighted decibels (dBA) was measured for 8 infant white noise machines and 6 iPhone applications selected by rating, review count, and cost. Testing was conducted using the NIOSH Sound Level Meter smartphone app at lowest and highest volume settings across three distances: 10 cm (simulating crib placement), 30 cm (outside crib rail), and 100 cm (nightstand across the room). Measured outputs were compared against the NIOSH occupational noise exposure threshold of 85 dBA.
What was found
At minimum volume, no device exceeded 85 dBA at any distance. At maximum volume and 10 cm distance, 9 of 14 (64.3%) devices exceeded 85 dBA. At 30 cm and 100 cm distances, no device exceeded 85 dBA at maximum volume.
Why it matters
White noise devices placed directly in a crib at maximal volume can emit sound levels exceeding adult occupational exposure limits. Keeping devices at least 30 cm away from the infant and avoiding maximum volume prevents exposure above recommended thresholds.
Limits
The study tested a small sample of 14 devices/apps and used a smartphone sound meter app rather than calibrated laboratory acoustic equipment. Findings compare outputs to adult occupational thresholds (85 dBA) rather than infant-specific auditory exposure guidelines, and the study did not measure real-world usage durations or clinical hearing outcomes.
Cited by
- supports Research recommends setting sound machines below 40 decibels, especially when used for children's sleep.