# TET

Terry_Clubbup
833 Posts

The characteristics of pink noise

For the purposes of this discussion, "power" means the average power or energy contained in a signal over a long period of time. White noise has the same distribution of power for all frequencies, so there is the same amount of power between 0 and 500 Hz, 500 and 1,000 Hz or 20,000 and 20,500 Hz.

**Pink[/b] noise has the same distribution of power for each octave, so the power between 0.5 Hz and 1 Hz is the same as between 5,000 Hz and 10,000 Hz. Since power is proportional to amplitude squared, the energy per Hz will decline at higher frequencies at the rate of about -3dB per octave. To be absolutely precise, the rolloff should be -10dB/decade, which is about 3.0102999 dB/octave. The uses of pink noise**

The most obvious use of

The most obvious use of

**pink noise [/b]is as an audio signal, to be used directly, to be filtered or to be used to modulate something. I am also interested in pink noise way below 1 Hz as a control signal for simulating randomly fluctuating aspects of music. For instance, I might want some aspect of a piece to fluctuate on a minute-by-minute basis, so I need random numbers with energy at 0.01 Hz and below. My particular interest is being able to sculpt such control signals from a****pink noise source[/b]**

purely by the use of filters. The idea would be that I could have a band-pass filter with a certain bandwidth in octaves (or fractions of an octave) and that I could choose to set its frequency as I liked, without affecting the RMS level of its output. Without a pink noise source ??? for instance by using a white noise source ??? it becomes very difficult to adjust the piece by changing the frequency of the sculpting filter, because this also affects the resultant signal level, Ideally, for control purposes (eg. "k" rate noise in Csound) I would like to be able to specify noise with: 1 - A certain lower bounding frequency. Eg. 0.1 Hz.[color:pink] Below that, there would either be little energy, or the energy would remain flat per Hz, rather than rising per Hz to give the 3dB/octave characteristic of pink noise. So it would be "white" below 0.1 Hz. [/color]

2 - A certain "RMS level per octave. For instance 5.0 RMS per octave. Therefore a perfect filter which excluded everything but an octave ??? no matter which octave above the lower bounding frequency ??? would average an RMS level of 5.0. Noise being noise, it would take a long time to average out the fluctuations to measure this accurately. 3 - It might also be desirable to specify an upper bounding frequency, to reduce computational load where high frequencies were not required.

In the future I intend to write a Csound / Quasimodo unit generator for "a" or "k" rate output, of an "industrial" quality, rather than "analytical" grade. Industrial or technical grade nitric acid specifies it being of a particular minimum and approximate strength. Analytical grade specifies exactly its strength and the tolerance for that specification, as well as noting the maximum permissible levels of the most important contaminants. Such parameters would be "i" rate: set at the start of the ugen's instantiate, not changeable over time. So specifying a lower limit frequency limit of the pink quality of the noise would result in that boundary being set to the nearest octave, not precisely. It is possible to conceive of a[color:pink] pink noise generator with "k" rate control of level, upper and lower boundary frequencies and the slopes of those boundaries.[/color] In this way, precise control over the noise frequency distribution could be achieved without changing the RMS level of the noise. I will leave this idea for now, but it would be mighty handy! Filtering white noise to make it pink

The simplest DSP filters are -6dB/octave. However, a DSP or analogue electronic low pass filter with a -3dB/octave response is (or rather, was) a rare beast indeed. Here are three filters which do the job. (Paul Kellet contributed two earlier filters to those listed here.) Such a filter would be fed with white noise to produce pink, within certain limits of accuracy. Below the algorithms is Allan Herriman's graphical analysis of the response of these three filters. The first description I am aware of is from Robert Bristow-Johnson posting to the Music-DSP list on 30 June 1998: This is rbj = (Red) Robert Bristow-Johnson's three pole and three zero filter.) another method that Orfanidis mentions came from a comp.dsp post of mine. it's just a simple "pinking" filter to be applied to white noise. since the rolloff is -3 dB/octave, -6 dB/octave (1st order pole) is too steep and 0 dB/octave is too shallow. an equiripple approximation to the ideal pinking filter can be realized by alternating real poles with real zeros. a simple 3rd order solution that i obtained is:

pole zero

---- ----

0.99572754 0.98443604

0.94790649 0.83392334

0.53567505 0.07568359

[color:pink]the response follows the ideal -3 dB/octave curve to within + or - 0.3 dB

over a 10 octave range from 0.0009*nyquist to 0.9*nyquist. probably if i

were to do it over again, i'd make it 5 poles and 4 zeros[/color]

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purely by the use of filters. The idea would be that I could have a band-pass filter with a certain bandwidth in octaves (or fractions of an octave) and that I could choose to set its frequency as I liked, without affecting the RMS level of its output. Without a pink noise source ??? for instance by using a white noise source ??? it becomes very difficult to adjust the piece by changing the frequency of the sculpting filter, because this also affects the resultant signal level, Ideally, for control purposes (eg. "k" rate noise in Csound) I would like to be able to specify noise with: 1 - A certain lower bounding frequency. Eg. 0.1 Hz.[color:pink] Below that, there would either be little energy, or the energy would remain flat per Hz, rather than rising per Hz to give the 3dB/octave characteristic of pink noise. So it would be "white" below 0.1 Hz. [/color]

2 - A certain "RMS level per octave. For instance 5.0 RMS per octave. Therefore a perfect filter which excluded everything but an octave ??? no matter which octave above the lower bounding frequency ??? would average an RMS level of 5.0. Noise being noise, it would take a long time to average out the fluctuations to measure this accurately. 3 - It might also be desirable to specify an upper bounding frequency, to reduce computational load where high frequencies were not required.

In the future I intend to write a Csound / Quasimodo unit generator for "a" or "k" rate output, of an "industrial" quality, rather than "analytical" grade. Industrial or technical grade nitric acid specifies it being of a particular minimum and approximate strength. Analytical grade specifies exactly its strength and the tolerance for that specification, as well as noting the maximum permissible levels of the most important contaminants. Such parameters would be "i" rate: set at the start of the ugen's instantiate, not changeable over time. So specifying a lower limit frequency limit of the pink quality of the noise would result in that boundary being set to the nearest octave, not precisely. It is possible to conceive of a[color:pink] pink noise generator with "k" rate control of level, upper and lower boundary frequencies and the slopes of those boundaries.[/color] In this way, precise control over the noise frequency distribution could be achieved without changing the RMS level of the noise. I will leave this idea for now, but it would be mighty handy! Filtering white noise to make it pink

The simplest DSP filters are -6dB/octave. However, a DSP or analogue electronic low pass filter with a -3dB/octave response is (or rather, was) a rare beast indeed. Here are three filters which do the job. (Paul Kellet contributed two earlier filters to those listed here.) Such a filter would be fed with white noise to produce pink, within certain limits of accuracy. Below the algorithms is Allan Herriman's graphical analysis of the response of these three filters. The first description I am aware of is from Robert Bristow-Johnson posting to the Music-DSP list on 30 June 1998: This is rbj = (Red) Robert Bristow-Johnson's three pole and three zero filter.) another method that Orfanidis mentions came from a comp.dsp post of mine. it's just a simple "pinking" filter to be applied to white noise. since the rolloff is -3 dB/octave, -6 dB/octave (1st order pole) is too steep and 0 dB/octave is too shallow. an equiripple approximation to the ideal pinking filter can be realized by alternating real poles with real zeros. a simple 3rd order solution that i obtained is:

pole zero

---- ----

0.99572754 0.98443604

0.94790649 0.83392334

0.53567505 0.07568359

[color:pink]the response follows the ideal -3 dB/octave curve to within + or - 0.3 dB

over a 10 octave range from 0.0009*nyquist to 0.9*nyquist. probably if i

were to do it over again, i'd make it 5 poles and 4 zeros[/color]

**Friday, April 29, 2005[/b]**TET TET

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## Comments

[color:white]White noise is a sound that contains every frequency within the range of human hearing [/color]

.[/b] (generally from 20 hertz to 20 kHz) [color:white]in equal amounts. Most people perceive this sound as having more high-frequency content than low, but this is not the case[/color]..[/b][color:white]This perception occurs because each successive octave has twice as many frequencies as the one preceding it[/color]..[/b][color:white]For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies[/color]..[/b][color:white]In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies.white noise

White noise is a sound that contains every frequency within the range of human hearing [color:white](generally from 20 hertz to 20 kHz) in equal amounts[/color].

.[/b][color:white]Most people perceive this sound as having more high-frequency content than low, but this is not the case[/color]. [color:white]This perception occurs because each successive octave has twice as many frequencies as the one preceding it[/color]..[/b][color:white]For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies[/color]. [color:white]In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies[/color]..[/b].[/b]

[color:white]White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles[/color].

.[/b][color:white]Pink noise is a variant of white noise[/color]..[/b][color:pink] Pink noise is white noise that has been filtered to reduce the volume at each octave[/color]..[/b][color:white]This is done to compensate for the increase in the number of frequencies per octave. [color:white]Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave[/color]..[/b][color:white] White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles. Pink noise is a variant of white noise[/color]..[/b].[/b][color:white] Pink noise is white noise that has been filtered to reduce the volume at each octave[/color]..[/b][color:white]This is done to compensate for the increase in the number of frequencies per octave[/color]. [color:white]Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave. [/color]

.[/b][color:white]white noise[/color].

[color:white]White noise is a sound that contains every frequency within the range of human hearing [/color](generally from 20 hertz to 20 kHz) [color:white]in equal amounts. Most people perceive this sound as having more high-frequency content than low, but this is not the case[/color].

.[/b] [color:white]This perception occurs because each successive octave has twice as many frequencies as the one preceding it[/color]..[/b] [color:white]For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies[/color]..[/b].[/b] [color:white]In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies.white noise

White noise is a sound that contains every frequency within the range of human hearing [color:white](generally from 20 hertz to 20 kHz) in equal amounts[/color]. [color:white]Most people perceive this sound as having more high-frequency content than low, but this is not the case[/color]. [color:white]This perception occurs because each successive octave has twice as many frequencies as the one preceding it[/color]. [color:white]For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies[/color].

.[/b][color:white]In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies[/color].

[color:white]White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles[/color]. [color:white]Pink noise is a variant of white noise[/color].

.[/b][color:pink] Pink noise is white noise that has been filtered to reduce the volume at each octave[/color]. [color:white]This is done to compensate for the increase in the number of frequencies per octave[/color]..[/b][color:white]Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave[/color]. [color:white] White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles. Pink noise is a variant of white noise[/color].[color:white] Pink noise is white noise that has been filtered to reduce the volume at each octave[/color]..[/b] [color:white]This is done to compensate for the increase in the number of frequencies per octave[/color]..[/b][color:white]Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave. [/color].[/b]white noise[/b]

White noise is a sound that contains every frequency within the range of human hearing (generally from 20 hertz to 20 kHz) in equal amounts. Most people perceive this sound as having more high-frequency content than low, but this is not the case. This perception occurs because each successive octave has twice as many frequencies as the one preceding it. For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies. In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies.

White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles.

[color:pink]

Pink noise is a variant of white noise. Pink noise is white noise that has been filtered to reduce the volume at each octave. This is done to compensate for the increase in the number of frequencies per octave. Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave[/b][/color]

[color:white]

white noise[/b]

White noise is a sound that contains every frequency within the range of human hearing (generally from 20 hertz to 20 kHz) in equal amounts. Most people perceive this sound as having more high-frequency content than low, but this is not the case. This perception occurs because each successive octave has twice as many frequencies as the one preceding it. For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies. In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies.

White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles.

Pink noise is a variant of white noise. Pink noise is white noise that has been filtered to reduce the volume at each octave. This is done to compensate for the increase in the number of frequencies per octave. Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave[/b][/color]

[color:white]

white noise[/b]

White noise is a sound that contains every frequency within the range of human hearing (generally from 20 hertz to 20 kHz) in equal amounts. Most people perceive this sound as having more high-frequency content than low, but this is not the case. This perception occurs because each successive octave has twice as many frequencies as the one preceding it. For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies. In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies.

White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles.

Pink noise is a variant of white noise. Pink noise is white noise that has been filtered to reduce the volume at each octave. This is done to compensate for the increase in the number of frequencies per octave. Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave[/b][/color]

[color:white]

white noise[/b]

White noise can be generated on a sound synthesizer. Sound designers can use this sound, with some processing and filtering, to create a multitude of effects such as wind, surf, space whooshes, and rumbles.

White noise is a sound that contains every frequency within the range of human hearing (generally from 20 hertz to 20 kHz) in equal amounts. Most people perceive this sound as having more high-frequency content than low, but this is not the case. This perception occurs because each successive octave has twice as many frequencies as the one preceding it. For example, from 100 Hz to 200 Hz, there are one hundred discrete frequencies. In the next octave (from 200 Hz to 400 Hz), there are two hundred frequencies.<marquee direction=down></marquee>

Pink noise is a variant of white noise. Pink noise is white noise that has been filtered to reduce the volume at each octave. This is done to compensate for the increase in the number of frequencies per octave. Each octave is reduced by 6 decibels, resulting in a noise sound wave that has equal energy at every octave[/b][/color]

There is a dangerous virtue in the word simplicity. And tonight I can understand a man wanting to die because nothing matters anymore when one sees through life completely. A man suffers and endures misfortune after misfortune. He bears them, settles into his destiny. People think well of him. And then, one evening, he meets a friend he has been very fond of, who speaks to him absent-mindedly. Returning home, the man kills himself. Afterwards, there is talk of private sorrows and secret dramas. No, if a reason really must be found, he killed himself because a friend spoke to him carelessly. In the same way, every time it seems to be that I've grasped the deep meaning of the world, it is its simplicity that always overwhelms me."HI DOODZ

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THESE BITCHES TET MY GANGSTA

I MENTIONED SOULSTRUT.COM IN A COVER LETTER.

IS THAT WAK?