You may have heard of white noise used to mask background sounds. Now, it has colorful competition.

There香蕉视频直播檚 a growing buzz around pink noise, brown noise, green noise 香蕉视频直播� a rainbow of soothing sounds 香蕉视频直播� and their theoretical effects on sleep, concentration and the relaxation response.

The science is new with only a few small studies behind it, but that hasn香蕉视频直播檛 stopped thousands of people from listening to hours of these noises on YouTube and on meditation apps that provide a palette of color noises with paid subscriptions.

WHAT IS PINK NOISE?

To understand pink noise, start with white, the most familiar of the color noises.

White noise is similar to static on a radio or TV. Sound engineers define it as having equal volume across all the frequencies audible to the human ear. It gets its name from white light, which contains all the visible color wavelengths.

But the high frequencies of white noise can sound harsh. Pink noise turns down the volume on those higher frequencies, so it sounds lower in pitch and more like the natural sound of rain or the ocean.

Brown noise sounds even lower in pitch, giving it a pleasing, soothing rumble.

Pink and brown, like white, have standard definitions to audio experts. Other color noises are more recent creations with very flexible definitions.

WHAT香蕉视频直播橲 THE SCIENCE BEHIND COLOR NOISES?

White noise and pink noise may provide small benefits for people with attention-deficit/hyperactivity disorder, according to a recent review of limited ADHD studies. In theory, it wakes up the brain, said ADHD researcher and co-author Joel Nigg of Oregon Health & Science University in Portland.

香蕉视频直播淭he noise provides stimulation to the brain without providing information, and so it doesn香蕉视频直播檛 distract,香蕉视频直播� Nigg said.

White noise has been used to treat ringing or buzzing in the ear, called tinnitus.

Scientists at Northwestern University are studying how short pulses of pink noise can enhance the slow brain waves of deep sleep. In small studies, these pink-noise pulses have shown promise in improving memory and the relaxation response.

Pink noise has a frequency profile 香蕉视频直播渧ery similar to the distribution of brain wave frequencies we see in slow-wave sleep because these are large, slow waves,香蕉视频直播� said Dr. Roneil Malkani, assistant professor of neurology at Northwestern University Feinberg School of Medicine.

If Northwestern香蕉视频直播檚 research pans out, it could lead to a medical device to improve sleep or memory through personalized pulses of pink noise. But many scientific questions remain unanswered, Malkani said. 香蕉视频直播淭here香蕉视频直播檚 still a lot of work we have to do.香蕉视频直播�

IS THERE ANY HARM IN TRYING COLOR NOISES?

If color noises feel calming and help you drown out distractions, it makes sense to use them. Keep them at a quiet level, of course, to prevent hearing loss and take 香蕉视频直播減lenty of breaks for the ears to rest,香蕉视频直播� Nigg said.

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The Associated Press Health and Science Department receives support from the Howard Hughes Medical Institute香蕉视频直播檚 Science and Educational Media Group. The AP is solely responsible for all content.

Carla K. Johnson, The Associated Press