字幕表 動画を再生する 英語字幕をプリント Some people need a little noise in the background when they're trying to get to sleep. If you're me, that means putting on Futurama in an endless loop until you know every episode word for word... in your sleep. But if you're a normal, healthy, functioning person, you might turn on some white noise. It turns out, though, there are more “colors” of noise, like pink, blue, and brown. How are these colors different, and what do they do to your brain while you sleep? Obviously sound has no color, unless you have synesthesia... in which case, awesome. But in this case it's helpful to use colors as an analogy for the spectrum of frequencies in noise. White light has all the colors of the rainbow equally represented, which is why it doesn't look like any one particular color. Likewise, the frequencies in white noise are all equally represented, with the lowest audible frequency at 20 Hz having the same power as all the frequencies above it, up to the highest frequency humans can hear, at 20,000 Hz. White noise sounds like this: [KSSSCK] There are natural sources of white noise, like steam hissing from a radiator or static from a TV. But if you're all modern with your gas furnace and digital TV and still can't sleep, then you can buy a white noise machine. Because white noise is all frequencies, it can help mask other noises, like the ringing of tinnitus or the sound of your girlfriend snoring... Katie. But humans don't hear all frequencies equally. The distance between 30 Hz and 60 Hz sounds the same as the distance between 10,000 Hz and 20,000 Hz; to us, both notes are one octave apart. And we're more sensitive to high-pitched noises, like babies crying. Enter pink noise. Unlike white noise, the energy in pink noise is highest for the low frequencies, and is halved every time the frequency doubles, meaning every octave has equal power and the net effect sounds less bright, and more balanced, than white noise. Here's white noise again: [KSSSCK] And here's pink noise: [WHOOOSH] While white noise is by far the most researched noise color, pink noise studies are on the rise recently. One from 2012 found that participants who listened to pink noise while they slept showed an improvement in deep sleep, and reported sleeping better. During deep sleep, the neurons in your brain are firing slowly, what's known as the delta brain wave pattern. As we age, we don't get as much deep sleep, which is associated with memory problems. So, a 2017 study played bursts of pink noise in sync with the delta brainwave to older adults, and found the waves increased in amplitude, and participants performed up to 30% better on memory tests. Why? Well, scientists are just beginning to explore the connection between sound and neural activity, but one thing's for sure -- the key to the results is timing, so if you're Philip J. Fry and don't have a delta brainwave, you're out of luck. That was a Futurama deep cut – y'gotta get on my level. The only other color noise that has an official Federal Communications standard definition is blue noise, which is like the opposite of pink noise, where higher frequencies are amped up. Wanna hear the most annoying sound in the world? [HISSS] Unofficially, there's also grey noise, where the high AND low ends are emphasized: [THURSSS] and Brown noise, where the frequencies mimic the randomness of Brownian motion: [WISSSH] Now, if you said that means the Brown noise is named after a person, not a color, you are you are technically correct... which is the best kind of correct. (Disappointingly, it has nothing to do with the mythical pitch that will make someone poop their pants.) There are even more sounds I don't have time to touch on, but it turns out there are a lot of colors of sound, and they have some surprising applications and effects that research is just starting to explore. So if you love science, make some noise! [KSSSCKWHOOOSHHISSSTHURSSSWISSSH] And if you REALLY love science, you better hit that subscribe button so you can catch all of our videos here on Seeker! Also, be sure to check out this awesome video about scientists that sift through COSMIC noise to identify alien signals. Thanks for watching!