Pink Noise Generator

This pink noise generator produces a random signal whose power falls off at −3 dB per octave from low to high frequency — equivalently, its power spectral density goes as 1/f. Pink noise is the broadband noise that contains equal power in every octave, which is why a spectrum analyser configured with a log-frequency axis (like the one below) shows it as a flat horizontal band. White noise, by contrast, has equal power per Hz and slopes upward by +3 dB/octave on the same display.

Why “equal power per octave” matters

Human hearing is roughly logarithmic in frequency — one octave (a 2× jump in Hz) is the same perceptual step whether it's 100→200 Hz or 5,000→10,000 Hz. Pink noise's flat-per-octave profile lines up with that perception, so it sounds balanced rather than “hissy” (white) or “rumbly” (brown). The same property is why pink, not white, is the standard test signal for audio measurement: it excites every octave with the same power so the room/speaker response is what the analyser is measuring, not the test signal's own bias.

Common uses

• Speaker / monitor calibration — flat-per-octave excitation paired with a real-time analyser shows the speaker's frequency response (deviations from flat) directly, without the +3 dB/oct correction needed with white noise. For precise single-frequency checks alongside a calibration sweep, use the online tone generator as the deterministic counterpart.
• Room-mode measurement and RT60 — pink noise excites low frequencies more than white, surfacing room modes, standing waves, and reverberation patterns at musically-relevant levels. A real-time octave-band analyzer will read well-calibrated pink noise as a flat row of bars, making response anomalies immediately visible.
• Sleep, focus, and tinnitus masking — the gentler high-frequency content (compared to white) is less fatiguing for long-session listening. Many sleep clinicians and audiologists recommend pink over white precisely because the reduced masking efficiency at high frequencies feels less intrusive.
• Broadcast and music production reference — pink's long-term average spectrum (LTAS) closely matches that of speech and music, so it doubles as a mix-bus loudness check. It is also the standard stimulus for measuring loudspeaker power handling (IEC 268-5).

How this generator works

The audio is produced by feeding uniform white noise through Paul Kellet's six-pole IIR filter, a canonical cascade of one-pole low-pass sections whose coefficients are tuned to approximate the 1/f power spectral density to within ±0.05 dB from ~9 Hz to ~22 kHz. The filter runs sample-by-sample inside the browser (no external library), and the output is written into a 2-second AudioBuffer that loops via a Web Audio AudioBufferSourceNode for indefinite playback at near-zero CPU. To see the time-frequency texture of the noise in detail — for example to confirm the flat spectral energy density across octaves — point the browser spectrogram tool at your speaker output while this generator plays.

About the “Compare colors” button

This plays three seconds each of white, pink, and brown noise in sequence so you can hear them back-to-back. White is the brightest (most upper-frequency content); pink sits in the middle; brown is deepest and rumbliest. Each colour uses its own generator: white via direct Math.random(), pink via the Kellet IIR cascade above, and brown via a leaky integrator on white (approximates −6 dB/octave).