Infant Sleep Machines: are they safe for baby's delicate hearing?
Made popular by sleep experts and parents, infant sleep machines (ISM's) have become "must-haves" on baby registries and wish lists.
These machines produce a white noise, natural wave or rain sounds, animals, cars, lullabies, heartbeats, and more. Manufacturers suggest that ISM's be placed near or on an infant crib to mask external sounds that may keep baby awake. For already sleep-deprived parents, ISM's may seem a win-win situation or quick fix.
A team of researchers at the University of Toronto and Sick Kids hospital set out to determine how loud these devices are and what impact they may have on a babies hearing and auditory development.
Here's what they found:
The current recommendations from manufacturers about safe use of infant sleep machines are vague. Instructions tell parents to play machines continuously and at a level equal to or louder than an infants cry. But there is next to no mention of potential risks and white noise exposure.
The study, measured the sound output from 14 infant sleep machines at distances of 30 cm, 100 cm, and 200 cm (to make placement of the machine on the crib rail, near the crib, and across the room). A sound level meter fitted with a coupler was used to stimulate the inner ear canal of an infant, no babies were used in the study.
For adults in the workplace, the noise exposure limit is 85 decibels over an 8-hour period. Exposure above that can lead to hearing loss. For infants, 50 dB (The level of normal conversation) over one hour is the recommended maximum safe exposure limit in hospital nurseries and neonatal intensive care units.
Results of the ISM study show that the 'in the crib' and 'beside the crib' distances, all 14 machines exceeded 50 dB over one hour. Three of those noise machines exceeded 85 dB. At the 'across the room' distance, 13 of 14 machines exceeded 50 dB.
They suggested that the consistent use of these machines raises concerns for increasing an infant's risk of noise induced hearing loss.
Summary - Are they safe?
ISM's can produce sound intensity in excess of the current recommendations for infants, which may place them at risk of noise-induced hearing damage in auditorial mal-development. Researchers say that, "the safe use of ISM's can be possible but requires policy recommendations for manufacturers, including limiting the maximum output levels."
Tips for parents:
- Place ISM's as far away from infants as possible (more than 2meters)
- When volume control is available, set the volume as low as possible to reduce the risk of noise-induced hearing damage
- Limit the duration of ISM use so that exposure is not continuous