"Noise" in signal processing is a random signal, and its color describes how its power is distributed across frequency — by analogy with visible light, where blue light carries more energy per photon than red. Each bar in this 3D chart is a frequency band; its height is that band's average power. Switching noise colors changes the shape of the spectrum, not just its loudness.
Pink noise's equal-energy-per-octave property matches how human hearing perceives loudness, which is why it's favored for audio equipment testing and sleep aids — while brown noise's deep rumble is a popular focus and relaxation sound.
A 3D frequency-spectrum bar chart that lets you switch between white, pink, brown and blue noise to see — and hear — exactly how each one distributes its power across frequency.
Each noise color follows a simple power law P(f) ∝ f^n. White noise is flat (n=0), pink falls off as 1/f, brown falls off faster as 1/f², and blue rises with frequency — the bar heights and the glowing spectrum curve trace that law live.
Pick a noise color from the dropdown, then press Play sound to hear a synthesized loop of that exact spectrum. Adjust bar count, jitter speed and the log/linear frequency axis, and drag to orbit the chart.
Pink noise carries equal energy per octave, which closely matches how the human ear perceives loudness across frequency — that's why it's the standard reference signal for testing loudspeakers and room acoustics.