What Is White Noise? Meaning, Examples, and Common Uses

White noise is a random signal or sound with all frequencies in a specific range with equal power, and has a flat power spectrum. In common speech, one can usually hear it as a consistent hiss or a sound of statical noise, that is, an untuned radio.

In signal processing and physics, white noise is a random signal with a constant power spectral density, or equally destructive power at all frequencies. The word is analogous to the white light, which has approximately the same intensity of all visible wavelengths.

Statistically, white noise can be modelled as a series of random values which are:

• No pattern predictable with time.

• Usually supposed to be of zero mean and finite variance.In some cases, this can be modeled as a Gaussian, which results in additive white Gaussian noise (AWGN) in communication theory.

How Does White Noise Sound?

Acoustically, white noise has the same intensity over the entire audible range (about 20 Hz, 20,000 Hz) hence no other pitch is prominent. To human ears this produces:

• A monotonous, non emphatic hiss or shhh sound.

• When no station is being tuned a similarity to the TV static or Radio noise.

• It does not have periodicity or melody; therefore, it does not sound as a tone, but as noise.

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Where White Noise Is Used?

The popularity of white noise in the science and engineering field, as well as in real life, is attributed to its remarkable nature of being equal in intensity to all frequencies.

White noises are commonly employed in everyday life in sound masking. Fans, air conditioners, special white-noise machines, etc. create the continuous background noise which can help to eliminate distractions like traffic, conversation, or unexpected sounds.

Acoustics and Sound Masking

• Applied in offices, hospitals, and bedrooms to conceal distraction noises (traffic, conversations) by applying a steady background noise.

• White or similar broadband noise is produced by commercial sound machines, fans, and apps to aid the sleeping or concentration of some individuals.

Electronics and Communications

Models random noise in circuit and communication paths and other disturbances attributed to thermal effects.

Used as a test signal to measure amplifier, speaker and microphone frequency response since it exites all frequencies equally.

Is White Noise Bad for Sleep?

White noise is not necessarily bad or always good to sleep, its impact varies depending on the situation of a person, the volume, and the surrounding. 

Studies indicate that it tends to enhance the quality of sleep by covering the disturbing sounds especially in high-noise environments, though there are possible negative effects in case of long-term or overuse.

Benefits Supported by Evidence

There are several studies that show a benefit of white noise in the initiation and maintenance of sleep:

• A 2021 study conducted at Weill Cornell has discovered that it substantially improved both subjective and objective sleep measurements (e.g. duration, efficiency), and that effects were maintained after exposure in urban noise settings.

• Meta-analyses of age (2025), infants benefited by 137 minutes of 24-hour total sleep time (TST) and night awakenings, and adults/elderly by 2.7-3.7 points Pittsburgh Sleep Quality Index (PSQI).

• In a clinical environment (ICU/non-ICU), it reduced PSQI by 2.6-4 points, which helped schizophrenia patients to reduce their sleep latency and anxiety.

• Mechanisms: Increases auditory threshold, facilitates drowsiness through stochastic resonance and regulates sleep cycles with no side effects of pharmaceuticals.

• Optimal volume: 40-60 dB (level of conversation), applied short-term.

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Statistical, Econometric and Modeling

• Represents the time-series model random error or innovation, which is an unforeseeable and not anticipated fluctuation not supported by the model.

• Applied as a baseline process in forecasting, filtering (e.g. Kalman filters), and control systems.

Researched in terms of its impact on sleep, focus, and learning, and with some there being the suggestion that it can facilitate the informal sleep of an infant, or the masking of tinnitus in patients in some instances.

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