I researched the two types of noises to find out which one is better to play on your sound machine while sleeping.

The big three in sleep sounds are white noise, brown noise, and pink noise, but there are many other noise types, including purple noise, gray noise, and even black noise (a.k.a. good ol ...

from gray noise to pink noise, that promote relaxation, and so many sound machines on the market come with dozens of sounds ...