We got a Dohm when my son was born. They generate the noise mechanically and are super soothing:
https://www.amazon.com/Marpac-Classic-White-Noise-Machine/dp...
Realized after we got it that it's what many of our massage therapists have used over the years in their offices.
My son's is 8 years old and going strong, used every night for peaceful sleep :)