I actually did not they had colors assigned to them, but I agree that brown is very relaxing.There are so many colors of noise, it's just weird to me. Brown is my favorite as it has an underlying tone of water. I literally cannot sleep with out it and neither can my dogs. They both know when its bed time and when the noise comes on. It's weird how our minds work. The stress from the day always plays back in mind in the evening when I go to bed. This seems to help me relax and not focus on work.