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What is the difference between white sound or noise and brown sound and does sound come in any other "colours?"
Question
#41939. Asked by gmackematix. (Dec 04 03 1:26 AM)
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Senior Moments
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I have just cut and pasted this so do not ask me to explain it.
A stream of random numbers constitutes "white" noise – if listened to as an audio signal. The "white" refers to the even distribution of wavelengths in white light, with a particular meaning in the audio or DSP sense: that the power of the noise is distributed evenly over all frequencies, between 0 and some maximum frequency which is typically half the sampling rate. For instance, white noise at a sampling rate of 44,100 Hz will have as much power between 100 and 600 Hz as between 20,000 and 20,500 Hz. To our ears, this seems very bright and harsh.
A 1996 treatise by Joseph S. Wisniewski on the "Colors of Noise", including white, pink, orange, green . . . is at: http://www.msaxon.com/colors.htm . (Also at this site, Martin Saxon's description of the various weighting schemes for measuring noise: http://www.msaxon.com/noise.htm .)
In the natural world, there are many physical processes which produce noise with what is known as a "pink" distribution of power. "Pink" noise has an even distribution of power if the frequency is mapped in a logarithmic scale. A straightforward example would be that there is as much noise power in the octave 200 to 400 Hz as there is in the octave 2,000 to 4,000 Hz. Consequently, it seems, our ears tell us that this is a "natural" even noise.
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gmackematix
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As I understand it, white noise or sound is a random mix of different frequencies of sound (known as notes) just as white light is a mixture of various frequencies of light (known as colours). An example would be the sound of interference on an untuned TV set.
The strangely named brown noise, on the other hand, is a progression from one note to the next.
If somebody was singing in the shower, the sound of water running would be white noise, while the singing would be brown noise.
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