Noise Generator (white, pink, brown)

What it is for

Pink noise is the standard test signal for speakers and room EQ because every octave carries the same energy. Brown noise is the deep rumble many people use to mask a noisy office or to sleep. White noise is the classic signal for testing filters and audio chains. This tool generates all of them, plus blue and violet noise, as a WAV file you can download and loop.

Each colour has a defined spectral slope: white 0, pink −3, brown −6, blue +3 and violet +6 dB per octave. The tool analyses the file it made and reports the measured slope, levels and octave bands, so you can check the colour yourself.

It is not a medical sleep or tinnitus treatment. For rain, wind and other textured sounds, use the Ambience Generator.

Worked example

For a background sound on a loop, we asked for brown noise, 30 s, 48 kHz, stereo, level −24 dBFS, seamless loop on and seed nap.

The summary: "Brown / red (−6 dB/octave) noise, 30 s stereo at 48000 Hz: measured slope −5.95 dB/octave (nominal −6), RMS −24 dBFS, peak −11.6 dBFS." The octave-band table falls steadily from 0 dB at 32 Hz to −16.6 dB at 1 kHz and −26.9 dB at 16 kHz, which is the brown slope. The loop check reported a largest jump of 0.002 at the seam, against 0.017 inside the file, so the restart is inaudible. The file is 5.76 MB (PCM 16-bit).

A second run shows the clip guard. White noise, 8 kHz mono, requested at −6 dBFS RMS, came back with a warning: "The requested level of −6 dBFS would have clipped, so the noise was made quieter (RMS −12.9 dBFS)." Gaussian noise has peaks about 13 dB above its average, so a loud RMS level cannot fit below full scale.

How to read the result

• Measured slope vs. nominal slope is the colour check. It is fitted over 1/3-octave bands from 100 Hz to 10 kHz (or a quarter of the sample rate). A value within about ±0.3 dB of the nominal slope is normal.
• RMS level is the average loudness of the file, including any fades. Peak level is the largest sample. The crest factor is the difference between them (about 12–14 dB for noise).
• Octave-band table: equal values mean pink noise. Rising values mean white, blue or violet noise, and falling values mean brown.
• Loop seam appears only for loops. A seam jump no bigger than the jumps inside the file means a click-free loop.

Tips and common mistakes

• Start playback quietly. Noise at −18 dBFS RMS through headphones turned up high is loud.
• Use pink noise for speaker and room measurements, brown for masking and sleep, and white for testing electronics.
• Keep the seed to recreate exactly the same file later. Change it if you need several different noise files of the same colour.
• For long listening, make a 30–60 s seamless loop and let your player repeat it, instead of a huge file.
• Choose 32-bit float only for editing software; 16-bit PCM plays everywhere.
• Very short files (under a second) give noisy slope estimates.

FAQ

Is pink noise made with the Voss-McCartney algorithm?

No. White noise goes through a chain of first-order filters designed for the chosen sample rate, with a pole every two octaves and a zero in between. That gives −3 dB per octave within a few tenths of a dB from 8 kHz up to 96 kHz sample rates.

Why are left and right different?

Stereo files use two independent random streams, so the noise sounds wide instead of sitting in the middle.

Will I get the same file again tomorrow?

Yes. The generator is fully deterministic: the same colour, settings and seed always produce the same bytes.

How long can the file be?

Up to 120 seconds, and up to 60 seconds for stereo at 96 kHz. The download stays available for about 2 hours.