White, Pink and Brown Noise Generator

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what is brown noise

What is brown noise (and why is it called that)

Pick Brown and look at the chart: the dashed line falls 6 dB per octave, twice as steep as pink. The resulting sound is deep and full, with almost no high-frequency hiss.

Random walk and 1/f²

Brown noise, also called red noise, is noise whose power spectral density is proportional to 1/f²: it falls 6.02 dB for each doubling of frequency. The name comes from Brownian motion, the random displacement of particles described by Robert Brown, not from the color brown. Mathematically, a random walk is the cumulative sum of independent steps, and the cumulative sum of white noise has exactly this spectrum. In practice, the lower the band, the more energy it has.
The tool generates brown as that accumulation, with one detail: a pure integrator would accumulate error and drift to huge values, so the calculation uses a leaky integrator with a 12 Hz corner frequency. Below it the spectrum is flat, which is below what speakers and headphones reproduce, and above it the fall is 6.02 dB per octave. The live measurement on the chart confirms the slope between 100 Hz and 8 kHz, and the tool's internal test requires less than 0.25 dB per octave of error.
Because it has so much energy in the bass, brown noise depends on equipment: phone and laptop speakers hardly reproduce anything below a few hundred hertz, and in that case the sound resembles pink. On headphones and speakers with bass, brown sounds like a deep rumble. Low frequencies are also tiring: the ear perceives them poorly, but the energy is there, so keep the volume low, especially on headphones, and prefer the noise level control to raising the system volume.

Brown in numbers

Slope

Input: dB/Hz
Expected output: -6.02 dB/oct

Proportional to 1/f².

Per decade

Input: 100 Hz vs 1000 Hz
Expected output: +20 dB at 100 Hz

Pink would have 10 dB and white 0 dB.

Between two octaves

Input: 100 Hz vs 400 Hz
Expected output: 12.04 dB

Two doublings of frequency, 2 x 6.02.

Integrator corner

Input: corner
Expected output: 12 Hz

Below it the spectrum is flat and does not drift.

Brown versus pink

Input: slope
Expected output: 3.01 dB/oct

Brown falls 6.02 and pink 3.01 dB per octave.

Full tool FAQ

What is the difference between white, pink and brown noise?

It is how energy is distributed across frequencies. White has equal power in every hertz and sounds hissy and bright. Pink falls 3.01 dB per octave and has equal energy in every octave, sounding more balanced, like steady heavy rain. Brown falls 6.02 dB per octave and sounds deep and muffled, like a distant waterfall. The chart in the tool shows these lines live.

What are blue, violet and grey noise?

Does white noise help you sleep or concentrate?

What volume should I use?

How does the sleep timer work?

How do I download the noise as WAV and how big is the file?

Are the rain, wind and ocean sounds recordings?

What is the dashed line on the chart?

Does it play with the screen locked or the tab in the background?

Do my presets and data leave my device?

Frequently asked questions

Are brown noise and red noise the same thing?

Yes, they are two names for the same kind of noise, with density proportional to 1/f² and a 6.02 dB per octave fall. The name brown comes from Brownian motion.

Why does brown sound the same as pink on my phone?

Because small speakers filter out the bass. What separates brown from pink is precisely the extra energy below a few hundred hertz, which does not come out of the device. On better headphones or speakers the difference shows.

Is brown noise safe to listen to for hours?

It depends on the volume, and the tool does not measure the real level. The WHO-ITU standard takes 80 dB for 40 hours per week as the adult reference. Start low, avoid headphones for long periods and prefer a speaker at a distance.

Next steps

Random walk and 1/f²

Brown noise, also called red noise, is noise whose power spectral density is proportional to 1/f²: it falls 6.02 dB for each doubling of frequency. The name comes from Brownian motion, the random displacement of particles described by Robert Brown, not from the color brown. Mathematically, a random walk is the cumulative sum of independent steps, and the cumulative sum of white noise has exactly this spectrum. In practice, the lower the band, the more energy it has.

The tool generates brown as that accumulation, with one detail: a pure integrator would accumulate error and drift to huge values, so the calculation uses a leaky integrator with a 12 Hz corner frequency. Below it the spectrum is flat, which is below what speakers and headphones reproduce, and above it the fall is 6.02 dB per octave. The live measurement on the chart confirms the slope between 100 Hz and 8 kHz, and the tool's internal test requires less than 0.25 dB per octave of error.

Because it has so much energy in the bass, brown noise depends on equipment: phone and laptop speakers hardly reproduce anything below a few hundred hertz, and in that case the sound resembles pink. On headphones and speakers with bass, brown sounds like a deep rumble. Low frequencies are also tiring: the ear perceives them poorly, but the energy is there, so keep the volume low, especially on headphones, and prefer the noise level control to raising the system volume.

Brown in numbers

Slope

Input: dB/Hz
Expected output: -6.02 dB/oct

Proportional to 1/f².

Per decade

Input: 100 Hz vs 1000 Hz
Expected output: +20 dB at 100 Hz

Pink would have 10 dB and white 0 dB.

Between two octaves

Input: 100 Hz vs 400 Hz
Expected output: 12.04 dB

Two doublings of frequency, 2 x 6.02.

Integrator corner

Input: corner
Expected output: 12 Hz

Below it the spectrum is flat and does not drift.

Brown versus pink

Input: slope
Expected output: 3.01 dB/oct

Brown falls 6.02 and pink 3.01 dB per octave.

Full tool FAQ

What is the difference between white, pink and brown noise?

What are blue, violet and grey noise?

Does white noise help you sleep or concentrate?

What volume should I use?

How does the sleep timer work?

How do I download the noise as WAV and how big is the file?

Are the rain, wind and ocean sounds recordings?

What is the dashed line on the chart?

Does it play with the screen locked or the tab in the background?

Do my presets and data leave my device?

Frequently asked questions

Are brown noise and red noise the same thing?

Yes, they are two names for the same kind of noise, with density proportional to 1/f² and a 6.02 dB per octave fall. The name brown comes from Brownian motion.