Instant A/B/C/D Acoustic Noise Color Comparator
Compare synthesized noise colors in real time with zero loop seams. Click any spectrum card below to switch or blend acoustic masking layers immediately.
1. Click to Compare Synthesized Noise Colors
What gives a noise its "colour"?
In audio engineering and physics, broadband random signals are named by analogy to light wavelengths. Just as white light contains all visible frequencies in equal measure, white noise contains equal acoustic power per hertz across the audible spectrum (20 Hz to 20,000 Hz). When engineers filter that random signal so energy rises or falls at a specific slope measured in decibels per octave (dB/octave), the timbre changes dramatically—from the bright hiss of white noise to the soft rainfall of pink noise and the deep thunderous rumble of brown noise.
Human hearing is logarithmic rather than linear: each octave doubles the frequency (for example, 100–200 Hz is one octave, while 4,000–8,000 Hz is also a single octave but spans forty times as many individual hertz). Because high-frequency octaves pack in thousands more hertz, flat white noise sounds piercing to the human ear, whereas pink and brown noise reduce high-frequency energy to match how our cochlea actually perceives pitch and loudness.
Complete noise colour comparison table
| Noise Colour | Spectral Slope | Power Density | How It Sounds | Best Practical Use |
|---|---|---|---|---|
| White noise | 0 dB / octave | Flat (1/f0) | Bright static, radio hiss, air conditioner fan | Masking high-pitched sudden sounds, consonant speech in offices, high-frequency tinnitus |
| Pink noise | −3 dB / octave | Equal per octave (1/f1) | Steady moderate rain, rustling leaves, soft wind | Overnight sleep maintenance, calm reading, calibrating room acoustics |
| Brown (Red) noise | −6 dB / octave | Brownian motion (1/f2) | Distant waterfall, heavy surf, pressurized cabin rumble | ADHD focus, quieting internal monologue, low-frequency traffic rumble masking |
| Deep brown noise | −9 dB / octave | Steep low-pass roll-off | Subwoofer warmth, distant thunder roll | Ultra-low-fatigue background warmth for sensitive ears and headphones |
| Green noise | Band-pass (~500 Hz) | Mid-spectrum centred | Forest canopy wind, river rapids without harsh hiss | Natural-sounding daytime concentration without heavy sub-bass or treble |
| Blue (Azure) noise | +3 dB / octave | Increases with frequency | Crisp mist spray, high-pitched pressurized steam | High-frequency tinnitus masking above 6,000 Hz |
| Grey noise | Psychoacoustic curve | Inverse A-weighting | Perceptually even across bass, mids and treble | Neutral acoustic masking tailored to human equal-loudness contours |
Why brown noise feels calmer than white noise for ADHD and study
When you listen to unfiltered white noise on headphones, nearly half of the total acoustic energy sits between 10,000 Hz and 20,000 Hz. The human ear canal naturally amplifies frequencies between 2,500 Hz and 5,000 Hz, making bright broadband static feel fatiguing after 15 to 20 minutes. Brown noise—named after Robert Brown's 1827 discovery of Brownian random walk, not the colour brown—integrates white noise mathematically so amplitude drops by 6 dB every time frequency doubles.
That −6 dB/octave slope removes virtually all piercing sibilance while preserving a dense, enveloping low-mid cushion between 60 Hz and 600 Hz. In cognitive psychology, the Moderate Brain Arousal (MBA) model (Söderlund et al., 2007, 2010) proposes that brains with lower tonic dopamine activity—common in ADHD—benefit from a steady floor of predictable stochastic stimulation via a phenomenon called stochastic resonance. Brown and pink noise provide that continuous acoustic floor without triggering the startle reflex.
Which noise colour blocks office speech and noisy neighbours best?
Choosing the right noise colour depends on the dominant frequency of the distraction you want to cover:
- Human voices and keyboard clatter (500 Hz – 4,000 Hz): Speech intelligibility lives in the upper midrange. Green noise or a 50/50 blend of pink and white noise covers consonant sounds ("s", "t", "k") far more effectively than pure brown noise.
- Footsteps, subwoofers and street traffic (40 Hz – 250 Hz): Low frequencies travel easily through walls. Layering brown noise with Deep Brown noise fills the bass region so intermittent thuds no longer stand out against silence.
- All-night sleep (Sleep Sounds): Pink noise (−3 dB/octave) and steady rain match the natural 1/f power distribution found in slow-wave brain activity and environmental soundscapes, making them ideal for 8-hour playback.
Frequently asked questions
Why is brown noise also called red noise?
Brown noise is short for Brownian noise, named after botanist Robert Brown, who described random particle motion in 1827. Physicists also call it red noise because its power is concentrated at the low-frequency end of the spectrum, just as red light sits at the low-frequency end of visible light.
Is green noise a real acoustic measurement or a marketing term?
While white, pink, brown and blue noise have strict mathematical definitions in signal processing, green noise refers practically to broadband noise band-pass filtered around the centre of the audible spectrum (roughly 500 Hz), mimicking the acoustic profile of foliage, wind and water in nature.
Can I mix two noise colours together in mindspeace?
Yes. Many users combine Brown noise (around 45%) for deep body with Pink or Green noise (around 20%) to mask midrange voices without making the overall sound harsh.
How does mindspeace generate noise without looping?
Our Web Audio engine generates fresh pseudo-random samples and runs them through precision biquad and Paul Kellet IIR filters in real time, so the audio stream never repeats.
Which noise colour is safest for overnight listening?
Pink noise or brown noise played at a low conversational volume (below 55 dB SPL) is gentle on the ears for overnight sleep.