Infant sleep machines and hazardous sound pressure levels

Infant "sleep machines" (ISMs) produce ambient noise or noise to mask other sounds in an infant's room with the goal of increasing uninterrupted sleep. We suggest that the consistent use of these devices raises concerns for increasing an infant's risk of noise-induced hearing loss. We therefore sought to determine the maximum output levels of these sleep machines.

Sound levels of 14 ISMs played at maximum volume were measured at 30, 100, and 200 cm from the machine using correction factors to account for a 6-month-old's ear canal.

Maximum sound levels at 30 cm were >50 A-weighted dB for all devices, which is the current recommended noise limit for infants in hospital nurseries. Three machines produced output levels >85 A-weighted dB, which, if played at these levels for >8 hours, exceeds current occupational limits for accumulated noise exposure in adults and risks noise-induced hearing loss.

ISMs are capable of producing output sound pressure levels that may be damaging to infant hearing and auditory development. We outline recommendations for safer operation of these machines.