I recently heard about a 2014 study by researchers at the University of Toronto that looked at 14 popular sleep machines and found that every single one was capable of producing sound levels that exceeded the limits set for hospital nurseries.
Here's a little piece of the article: These machines are capable of delivering noise that we think is unsafe for full-grown adults in mines,said Dr. Blake Papsin, the senior author of the paper and the chief otolaryngologist at the Hospital for Sick Children in Toronto.
Wow! So, if you have a noise machine (fan, white noise, digital, etc.), please make sure it is not too loud! I actually heard about it from this new product on Kickstarter called SNOOZ. These guys have created a new white noise machine that has a nursery calibration app to tell you if the sound is too loud for your babies ears! How awesome is that?!
They quoted another article on their page that said: "In a randomized trial of newborn babies, researchers found that babies were 25-80% more likely to fall asleep when exposed to white noise." Needless to say, I just supported them and bought a SNOOZ. Even if you don't want to, it might be worth your time to check out some of their research on white noise and the safety and effects it has on your baby. Here's the page: https://www.kickstarter.com/projects/snooz/snooz-sound-sleep
Don't turn those fans and noise machines up too loud