White, Pink, and Brown Noise in Audacity Explained

Audacity includes a built-in noise generation tool capable of producing white, pink, and brown noise. While these options may seem similar at first glance, each type is defined by a distinct mathematical distribution of frequencies across the audio spectrum. This article outlines the key differences in energy distribution, sound profile, and practical applications among the three noise types available in Audacity's generator menu.

Accessing the Generators in Audacity

To create any of these noise profiles in Audacity, navigate to Generate > Noise... from the top menu. In the dialog box that appears, you can choose between White, Pink, and Brownian (commonly referred to as Brown) from the Noise type dropdown, as well as set the amplitude and duration.

White Noise

• Energy Distribution: White noise has equal energy per hertz across all audible frequencies from 20 Hz to 20,000 Hz. Its power spectral density is completely flat (0 dB per octave slope).
• Perceived Sound: Because the human ear hears frequencies logarithmically, having equal energy at every single hertz means higher octaves contain significantly more total energy than lower octaves. As a result, white noise sounds bright, sharp, and hissy, similar to an untuned analog television or radio static.
• Common Uses in Audacity:
  • Audio gear calibration and testing.
  • Creating percussion elements in synthesis, such as synthesized snare drums, hi-hats, and wind effects.
  • Testing microphone frequency response and measuring room reverberation times.

Pink Noise

• Energy Distribution: Pink noise decreases in power by 3 dB per octave (or roughly 10 dB per decade) as frequency increases. This creates equal energy per octave rather than equal energy per single hertz.
• Perceived Sound: Human hearing perceives sound on a logarithmic scale, making pink noise sound balanced, even, and natural across all frequency ranges. It lacks the harsh, piercing high end of white noise and sounds similar to steady, rushing rainfall or moderate wind.
• Common Uses in Audacity:
  • Room acoustic calibration and equalization, as it matches how human ears naturally perceive volume across the spectrum.
  • Audio mastering references to verify spectral balance.
  • Sound masking for focus, study environments, and treating hyperacusis or tinnitus.

Brown (Brownian) Noise

• Energy Distribution: Brown noise—labeled as Brownian in Audacity—drops by 6 dB per octave (or 20 dB per decade) as frequency rises. Its name originates from Brownian motion (the random motion of particles) rather than a color association.
• Perceived Sound: Due to the steep high-frequency roll-off, brown noise possesses the lowest energy in the treble range and the highest energy in the bass range. It sounds deep, warm, and muffled, closely resembling distant thunder, heavy surf, or the low roar of an airplane cabin.
• Common Uses in Audacity:
  • Background soundscapes for deep sleep, meditation, and blocking low-frequency interruptions like traffic.
  • Sound design bases for simulating natural phenomena such as avalanches, explosions, or heavy waterfalls.
  • Masking internal ear sounds (such as low-pitch tinnitus) without causing ear fatigue.

Summary Comparison