You may have heard the phrase “white noise.” But what does it mean?
When there’s a lot of different sound signals at once, we often consider it “noise.”
Noise has an inherent randomness.
It’s a mix of unpredictable signals.
But there are different varieties of noise—patterns within that randomness.
When a cat makes that “sss” sound, zillions of air molecules create sound across a broad range of frequencies.
We call it white noise because it has basically equal power for all frequencies of audible sound—just like white light has equal power for all frequencies of visible light.
And just as we call different frequencies of light different colors, we call different mixes of sound frequencies different colors of noise.
When we use our mouths to make the sound “shhh,” we get pink noise.
Pink noise is shaded more toward the low end of the spectrum.
That makes it a popular choice for people looking for background noise to drown out distractions.
Or to help them relax.
Although white noise has a flat spectrum, it can sound a little jarring and high-pitched.
That’s because our ears are more sensitive to the higher frequencies, so those feel louder.
Pink noise may be more soothing because it boosts lower frequencies, so it sounds more natural.
And it’s similar to the background noise of our mother’s womb—a loud, low rumble.
The comforting sound of life itself.
Writer and Narrator: Eli Kintisch
Animator: Shelley Sandiford
Supervising Editor: Lydia Chain
Sound: Getty, Parga et al. A description of externally recorded womb sounds in human subjects during gestation. PLOS One.