White noise is a type of sound that contains all the frequencies across the entire spectrum of audible sound in equal measure, producing a consistent, steady "shhh" or static-like sound similar to the noise from an untuned radio or television
. It is called "white" noise by analogy to white light, which contains all colors (frequencies) of visible light combined
. In technical terms, white noise has equal intensity at different frequencies, resulting in a flat power spectral density, meaning that all frequencies are present at the same power level
. This makes white noise a broadband sound that covers the full range of human hearing. White noise is often used to mask other sounds because its steady, unvarying nature can help reduce distractions from sudden noises, making it useful for improving sleep, concentration, and calming infants
. It acts as a background sound that can help create a more peaceful environment by covering up disruptive ambient noises. There are other "colors" of noise related to white noise, such as pink noise and brown noise, which differ in how their power is distributed across frequencies, but white noise specifically has equal power across all frequencies
. In summary, white noise is a sound containing all audible frequencies played together at equal intensity, creating a steady, uniform sound often used to mask other noises and aid relaxation or sleep.
