White, Pink and Brown Noise Generator

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pink noise vs white noise difference

Pink noise or white noise: what is the difference?

Play white, then pink, and compare the chart: white is a straight horizontal line, pink falls 3 dB each time the frequency doubles. The difference is only in how the same energy is split between lows and highs.

Power per hertz versus energy per octave

The confusion comes from two ways of measuring. White noise has the same power in every hertz: if you filter a band 100 Hz wide anywhere in the spectrum, the energy is equal. The ear and music, though, work in octaves, and each octave is twice as wide as the previous one: 100 to 200 Hz is 100 Hz wide, 1600 to 3200 Hz is 1600. So a high octave of white noise carries more total energy than a low one, and it sounds hissy.
Pink noise fixes that: power per hertz falls with frequency (proportional to 1/f), exactly what is needed for every octave to have the same energy. In decibels the density falls 3.01 dB for each doubling of frequency, or 10 dB each time the frequency is multiplied by ten. To the ear the result sounds more balanced and lower than white. The tool's chart shows density per hertz on a logarithmic frequency scale: white is the horizontal line, pink the descending line.
Generating both is simple: white comes from uniform random numbers; pink runs white through a Paul Kellet filter, which according to its author follows the 1/f curve to within ±0.05 dB above 9.2 Hz at 44.1 kHz. Here both come out at the same RMS level, so switching from one to the other does not change the volume. If pink sounds quieter on your device, it is because small speakers reproduce poorly the bass range that pink has in greater supply.

Differences in numbers

White slope

Input: dB/Hz
Expected output: 0 dB/oct

Horizontal line on the chart.

Pink slope

Input: dB/Hz
Expected output: -3.01 dB/oct

Half the power at each doubling of frequency.

White: low octave vs high octave

Input: 100 a 200 Hz vs 3200 a 6400 Hz
Expected output: +15.05 dB

The high band is 32 times wider (five octaves, 5 x 3.01).

Pink: low octave vs high octave

Input: 100 a 200 Hz vs 3200 a 6400 Hz
Expected output: 0 dB

Same energy in every octave.

Pink per decade

Input: 100 Hz vs 1000 Hz
Expected output: +10 dB at 100 Hz

Density per hertz, same total level.

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

Which one is more pleasant to listen to?

It is a matter of preference. Pink has more bass and usually sounds softer; white sounds hissier. Try both at the same volume and keep the one that bothers you less. Keep the volume low in both cases.

Where does brown noise fit in?

Brown continues the sequence: it falls 6.02 dB per octave, with even more bass than pink. From brightest to deepest the order is violet, blue, white, pink, brown.

Do white and pink have the same volume in the tool?

Yes, both are generated at the same RMS level. The perceived loudness may still differ, because the ear is not equally sensitive at all frequencies.

Next steps

Power per hertz versus energy per octave

The confusion comes from two ways of measuring. White noise has the same power in every hertz: if you filter a band 100 Hz wide anywhere in the spectrum, the energy is equal. The ear and music, though, work in octaves, and each octave is twice as wide as the previous one: 100 to 200 Hz is 100 Hz wide, 1600 to 3200 Hz is 1600. So a high octave of white noise carries more total energy than a low one, and it sounds hissy.

Pink noise fixes that: power per hertz falls with frequency (proportional to 1/f), exactly what is needed for every octave to have the same energy. In decibels the density falls 3.01 dB for each doubling of frequency, or 10 dB each time the frequency is multiplied by ten. To the ear the result sounds more balanced and lower than white. The tool's chart shows density per hertz on a logarithmic frequency scale: white is the horizontal line, pink the descending line.

Generating both is simple: white comes from uniform random numbers; pink runs white through a Paul Kellet filter, which according to its author follows the 1/f curve to within ±0.05 dB above 9.2 Hz at 44.1 kHz. Here both come out at the same RMS level, so switching from one to the other does not change the volume. If pink sounds quieter on your device, it is because small speakers reproduce poorly the bass range that pink has in greater supply.

Differences in numbers

White slope

Input: dB/Hz
Expected output: 0 dB/oct

Horizontal line on the chart.

Pink slope

Input: dB/Hz
Expected output: -3.01 dB/oct

Half the power at each doubling of frequency.

White: low octave vs high octave

Input: 100 a 200 Hz vs 3200 a 6400 Hz
Expected output: +15.05 dB

The high band is 32 times wider (five octaves, 5 x 3.01).

Pink: low octave vs high octave

Input: 100 a 200 Hz vs 3200 a 6400 Hz
Expected output: 0 dB

Same energy in every octave.

Pink per decade

Input: 100 Hz vs 1000 Hz
Expected output: +10 dB at 100 Hz

Density per hertz, same total level.

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

Which one is more pleasant to listen to?

Where does brown noise fit in?

Brown continues the sequence: it falls 6.02 dB per octave, with even more bass than pink. From brightest to deepest the order is violet, blue, white, pink, brown.

Do white and pink have the same volume in the tool?

Yes, both are generated at the same RMS level. The perceived loudness may still differ, because the ear is not equally sensitive at all frequencies.