Where each colour puts its energy
The noise colours differ in one thing: how energy is distributed across the spectrum. White noise is flat. Pink falls 3 dB per octave, brown falls 6 — which puts almost all of brown’s audible energy below 500 Hz. Blue and violet rise towards the treble instead. Everything else is a shaped variant: a band lifted, a band cut, or a weighting applied to match the ear.
The analyser below is measuring, not drawing. It taps the real signal chain — the same generator, the same colour filter and the same 35 Hz high-pass the players use — so the curve is what this site actually outputs. That high-pass is the roll-off you will see at the far left of every colour.
Colour
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Audio is off until you turn it on. Last updated 2026-10-07.
The numbers behind each curve
The actual values this site runs. Published because no other free noise generator states its filter settings, which makes it impossible to tell whether two sites playing “green noise” are playing anything like the same signal.
| Colour | Base slope | Filter | Centre | What it does |
|---|---|---|---|---|
| Brown Noise | 0 dB/octave — flat | lowpass · Q 0.5 | 400 Hz | Rolls off everything above the cutoff, leaving the low end. |
| White Noise | 0 dB/octave — flat | none | — | Nothing — the base noise is the output. |
| Pink Noise | −3 dB/octave | peaking · Q 0.3 | 1000 Hz | Lifts a band around the centre by 6 dB, leaving the rest alone. |
| Green Noise | 0 dB/octave — flat | bandpass · Q 0.8 | 700 Hz | Keeps a band around the centre and attenuates both sides. |
| Blue Noise | 0 dB/octave — flat | highpass · Q 0.5 | 2000 Hz | Rolls off everything below the cutoff, leaving the top end. |
| Grey Noise | 0 dB/octave — flat | peaking · Q 0.7 | 3000 Hz | Lifts a band around the centre by 6 dB, leaving the rest alone. |
| Violet Noise | 0 dB/octave — flat | highpass · Q 0.3 | 4000 Hz | Rolls off everything below the cutoff, leaving the top end. |
| Orange Noise | 0 dB/octave — flat | notch · Q 1 | 1500 Hz | Cuts a band around the centre, leaving the rest alone. |
| Red Noise | 0 dB/octave — flat | lowpass · Q 0.4 | 300 Hz | Rolls off everything above the cutoff, leaving the low end. |
| Yellow Noise | 0 dB/octave — flat | peaking · Q 1.2 | 1500 Hz | Lifts a band around the centre by 6 dB, leaving the rest alone. |
Every colour starts from one of three generators — uniform random samples for white, a Paul Kellet 7-pole approximation for pink, a leaky integrator for brown — then gets one biquad and the 35 Hz high-pass. Buffers are 8 seconds, generated per session and crossfaded at the seam, so nothing loops audibly. The full signal chain is on the about page.
How to read the curves
The x-axis is logarithmic. Each gridline is a step in frequency, not a fixed number of hertz, because hearing works that way — the gap between 100 and 200 Hz is one octave, and so is the gap between 5 and 10 kHz. A linear axis would squeeze nine tenths of what you can hear into the right-hand edge.
A flat line means white noise. Equal energy at every frequency. It is the reference, and the reason white noise masks the widest range of intrusions: no band is left uncovered.
A line falling to the right means a warmer colour. Pink falls gently; brown falls at twice the rate and is visibly concentrated on the left. That concentration is why brown is the only common colour that masks traffic, snoring and footsteps — and why it feels gentler than it measures, since the ear is least sensitive exactly there.
A line rising to the right means a brighter colour. Blue and violet put their energy where high-frequency tinnitus and squeaks live, which is the only place those can be masked. Brown noise cannot touch them.
A bump or a dip means a shaped colour. Green lifts the midrange where outdoor ambience sits. Orange cuts a notch where musical tones live, which is what makes it the one colour that masks music rather than noise.
Frequently asked questions
What is the difference between the noise colours?
Where the energy sits across the spectrum. White noise has equal power at every frequency. Pink falls 3 dB per octave. Brown falls 6 dB per octave, which puts almost all of its audible energy below 500 Hz. Blue and violet rise towards the treble instead. The rest — green, grey, orange, red, yellow — are shaped variants: a band lifted, a band cut, or a weighting applied to match the ear.
Why does brown noise sound quieter than white noise at the same volume?
Because the ear is least sensitive to the frequencies where brown noise puts its energy. Equal-loudness contours fall off steeply below a few hundred hertz, so a signal concentrated under 500 Hz reads as roughly 15 to 20 dB gentler than it measures. This is the single most common reason people play brown noise louder than they intend to.
Is this spectrum measured or calculated?
Measured. An AnalyserNode taps the real signal chain — the same generator, the same colour filter, and the same 35 Hz high-pass the players use — so the curve is the site's actual output rather than an idealised version of it. The 35 Hz high-pass is visible as the roll-off at the far left of every colour.
Which noise colour covers the widest frequency range?
White noise, by definition: equal power at every frequency means no band is left uncovered. That even coverage is why it is the better choice when the sounds you are masking are varied and unpredictable. It is also why it sounds bright — there are far more high frequencies than low ones in the audible range, and the ear is most sensitive in the upper midrange.
Why is there a roll-off below 35 Hz on every colour?
It is deliberate. Content below about 35 Hz is inaudible on phone and laptop speakers, but the driver still tries to move for it, and that wasted excursion is heard as rattle or buzz instead of bass. A 35 Hz high-pass at Q 0.707 removes what no small speaker can reproduce and leaves the audible low end intact.