Have you ever come to a dryer in operation and your baby has calmed down? Some appliances, which have a rotor system, can emit white noise when they reach certain revolutions, since that sound covers almost the entire spectrum.
You can use a dryer, extractor hood, washing machine, dishwasher, refrigerator or radio tuned to a point on the dial where there is no emission.
We can also find applications for both iOS and Android, with which to get a white noise source.
Also, there is a smart cradle called Snoo on the market , which, in addition to being able to rock the baby when it moves a lot or when it starts to cry, emits white noise.