I don't think there's a need to specifically purchase a machine for that. You can just hug your baby close and do a "shhh" sound in his ear. I downloaded a white noise app too, but it wasn't very effective for my baby as she cried when she needed to (i.e. hunger, dirty nappy, scared), so white noise wouldn't stop the cause of her crying.
Yes! A study on PubMed found that 80% of babies exposed to white noise fell asleep in a given time period (4.5 minutes) while only 25% of babies not exposed to it fell asleep in the same period. The study says this is likely due to white noise's similarity to intrauterine sound—i.e., what a fetus hears in the womb.
You can download apps from iphone/samsung. It's free and easy to use. There are hairdryer, water flows, vacuum and other different kind of white noises.
Yes they are recommended - They make all the difference in drowning out loud neighbors, cars, sirens! We own 3 machines in our household!!!
thanks