So, I did a little research and found an article from the journal Science in 2003. A study from the University of CA at San Francisco (UCSF) actually looked at baby rats who listened to white noise for prolonged periods of time. The researchers found that the part of the auditory cortex (in rats) that is responsible for hearing, did not develop properly after listening to the white noise. Interestingly, when the white noise was taken away, the brain resumed normal development. Again, this study was in baby rats, and to my knowledge has not been duplicated. But, these baby rats were exposed to hours on end of "white noise which may not be the same thing as sleeping with a sound machine at night. We might need to be more concerned about background white noise. We do know that babies learn language by listening and absorbing human speech. They need to hear their parent's talking to them from the time they are born. They listen to not only their parent's speech, but also to siblings, grandparents etc. and from an early age respond to that language by making cooing sounds themselves, often imitating the sounds they have heard. They are also exposed to a great deal of white noise or background noise with the televisions being on, computers, telephones, vacuum cleaners, lawn mowers etc. going on all day. The white noise that may be reduced by turning off televisions, videos, computers etc and replacing that background noise with human speech through reading, singing and just talking to your baby and child could only be beneficial. One might surmise that white noise in the form of a sound machine at night would not affect a child's speech development, as this is not a time for language acquisition. Having a good bedtime routine, reading to your child before bed, or singing them a lullaby will encourage language development, and the sound machine may ensure a good night's sleep. Just turn it off in the morning! That's your daily dose for today. We'll chat again tomorrow. Send Dr. Sue your question or comment!