Fun fact: Noise has color too!

Yes, noise has color! The color of noise is actually the energy spectrum of the noise signal; different colors of noise have different frequency domains.

1 White noise

White noise is a random signal or process with a constant power spectral density, meaning that the power of its frequency components is uniform across the entire audible frequency range (0-20 kHz). Its power spectrum is similar to that of white light (which contains all colors of light) and is used to measure the sensitivity and resonance of loudspeakers and headphones.

2 Pink noise

Pink noise (also known as pink noise or 1/f noise) refers to noise with equal intensity across all octaves; that is, within a certain frequency range (such as an octave), pink noise has the same or similar energy. The lower frequency range has higher energy and can be used to simulate the sound of traffic.

3. Red noise (oceanographic concept)

Red noise is caused by Brownian motion and is also known as random motion noise. It is a type of noise associated with the marine environment, and is called red noise because it selectively absorbs higher frequencies. To most people, red noise may sound similar to pink noise, but some describe it as more powerful.

4 Orange noise

Orange noise is a quasi-static noise with a finite power spectrum and a finite number of zero-power narrowband signals across the entire continuous frequency range. These zero-power narrowband signals are concentrated at the center of the note frequencies in any correlated note system. Because this noise eliminates all harmonics, the remaining spectrum is called the "orange" note, hence the name orange noise.

5 Blue noise

Blue noise is a type of noise with higher energy at high frequencies and lower energy at low frequencies. Its spectral characteristics show that the energy gradually increases with frequency. For high-frequency signals, it is considered benign noise.

6 Purple Noise

Purple noise exhibits the opposite spectral characteristics to red noise. Spectrally, purple noise has higher energy in the high-frequency range, while its energy gradually decreases in the low-frequency range. This spectral distribution makes purple noise more prominent in the high-frequency region.

7. Gray noise

Grey noise is designed to conform to the "equal loudness curve" of the human ear. The human ear is sensitive to different frequencies of sound at different levels, and the spectrum of grey noise is designed entirely according to this equal loudness curve. Specifically, grey noise has more energy in the frequency range where human hearing is less sensitive (usually the low and high frequencies), and relatively less energy in the frequency range where hearing is sensitive (the mid-frequency range).

8. Brown noise (drift noise | drunken noise)

Within a finite frequency range excluding DC components, power density decreases by 6 dB per octave with increasing frequency (density is inversely proportional to the square of the frequency). This noise is actually generated by Brownian motion; it is also known as random drift noise or drunken noise.

9. Black noise (no noise)

Noise with a constant power density in a finite frequency range above 20 kHz is somewhat similar to ultrasonic white noise. This black noise, like "black light," is imperceptible due to its high frequency, but it still affects you and your surroundings. It has an fβ spectrum, where β > 2. Experience suggests that this noise is highly hazardous.

Article forwarded from: Dr. Sound