New York Times on the "cult of brown noise" aficionados

White noise is static, a blend of all audible frequencies. It's hissy and harsh. I prefer brown noise, which attenuates higher frequencies and increases lower frequencies, giving it a richer sound. According to The New York Times, brown noise "gained a fervent following over the summer, picking up speed in online A.D.H.D. communities… Many said it allowed their brains to feel calm, freed from an internal monologue."

Those with A.D.H.D. may not have enough dopamine in their brains, a chemical that impacts attention and motivation, [Yamalis Diaz, an assistant professor in the department of child & adolescent psychiatry at N.Y.U. Langone Health, who specializes in A.D.H.D.] said. Without enough dopamine, the brain stays "hungry" while you're trying to concentrate, Dr. Diaz explained. "While one part of the brain is trying to focus, the other part of your brain is looking for food." When you listen to a sound like brown, pink or white noise, "you're almost assigning the circuits a task," she said. "'You listen to this, while I focus on this task.'"

Here is a fun colored noise generator you can use to mix a noise cocktail of your choice.