[Noise] as Color.

Have you ever heard of brown noise?



( <--- brown noise wave form!)

Apparently there is such a thing as brown noise, and I was told by Lisa and Pearry that it causes people to lose control of their bowels... brown.

According to the internet, brown noise is a random noise which mimics the signal noise produced by brownian motion. Technically speaking, the spectral density is proportional to 1/f², which basically means it has more energy at lower frequencies (decreasing by around 6dB per octave). To the human ear, brown noise is similar to white noise but at a lower frequency. Examples in nature include waves on the beach and some wind noise.

For my education, and yours:

There is white and pink noise, which are the two terms you most often hear in the audio industry. Generally, they are used for balancing speakers. However, there is blue noise, orange noise, even green noise.

Terminology:

White noise is a random noise that contains an equal amount of energy in all frequency bands. It is the equivalent to white light, hence the name.

Pink noise is similar to white noise except that it contains an equal amount of energy in each octave band. It's also called 1/f noise or flicker noise.

Red noise is either an oceanographic term which describes the ambient noise of distant underwater objects or another term for brown noise. The term red reportedly refers to the loss of higher frequencies and the emphasis on lower frequencies.

Purple noise is similar to brown noise except that the power density increases 6 dB per octave as the frequency increases.

Orange noise is a bit more complicated. The semi-official definition of orange noise is "a quasi-stationary noise with a finite power spectrum with a finite number of small bands of zero energy dispersed throughout a continuous spectrum." We have not been able to determine where this definition originated but it is commonly used in reference material. Orange noise relates to musical scales. The bands of zero energy coincide with the notes in the scale. In effect this means that the in-tune notes of a scale are removed, leaving only the out-of-tune frequencies. This creates a clashing, displeasing noise.

Blue noise, or azure noise, is similar to pink noise except the power density increases 3 dB per octave as the frequency increases. In technical terms the density is proportional to f (frequency).

Black noise has various definitions... but my favorite is silence, no sound at all (flat line). It is also said to be a noise which has zero energy... maybe that's why Lisa keeps referring to everything in terms of energy. She said the old AES suites (in the houses that were recently flattened) had such a gigantic energy level. I never thought about everything as energy... I have always pictured fractions and waves instead.

Oh, and I forgot my favorite... green noise, loosely defined as the background noise of the world.

I find green noise soothing, and can't sleep without it.