NoiseWiki - User contributions [en]

Distortion

2014-08-03T20:39:18Z

Cacofono:

<div style="font-family: serif; text-transform: capitalize;">
Distortion can refer to a variety of mathematically distinct effects, referring to an aesthetic associated with warmth, fuzziness, dirtiness, harshness.

One generic method for achieving distortion digitally is to use a "non-linear transfer function" (NLTF), a memoryless filter that maps amplitudes from an input signal to an output signal according to a deterministic function. As the name implies, we exclude any boring linear functions that only serve to amplify or attenuate. Many non-linear transfer functions can be used, with different effects:

* f(x) = x if -1 < x < 1; -1 if x < -1; 1 if x > 1 is "clip distortion," which can occur naturally when digital audio caps. It is ringy and tends to add odd harmonics. (It only has any effect when the signal is amplified so that it peaks beyond [-1,1].)
* f(x) = x if -1 < x < 1; -x - 2 if x < -1; -x + 2 if x > 1 is "fold distortion," which is similar to clip distortion but even buzzier.
* f(x) = x if -1 < x < 1; x + 2 if x < -1; x - 2 if x > 1 is "wrap distortion," which is buzzier and harsher still than fold distortion.
* f(x) = tanh(x) (hyperbolic tangent) is quite a bit like clip distortion, but much, much subtler. It is a form of "soft clipping."
* f(x) = 0 if x = 0; 1 - x if x > 0; -1 - x if x < 0 is "inside-out distortion," which generates ''extremely'' abrasive and noisy audio. Good shit.

Stephen McGovern provides an [http://sgm-audio.com/research/dist/dist.html interesting algorithm] for distortion that results in an infinite family of NLTFs. The formula is, given an odd positive integer n: f(x) = (sin(arcsin(x)) + sin(3 arcsin(x))/3 + sin(5 arcsin(x))/5 + sin(7 arcsin(x))/7 + ... + sin(n arcsin(x)) / n) * 2/pi. As n approaches infinity, the sound becomes similar to extreme amplification + clipping, since the formula is essentially a Fourier series for a square wave. Small values of n produce a milder effect that's still interesting. By fading out each partial for in-between values of n, the distortion can be smoothly modulated with ease.

Not all distortion effects are NLTFs. Here are some others:

* [[Decimation]] reduces the sample rate or bit depth.
* Trevor Wishart describes an algorithm where a signal is sliced into zero-crossings and some sections are silenced. If the silencing is periodic, it sounds like a sort of "purring." Interesting enough, but the real fun begins when the silencing is random, yielding very noisy sounds reminiscent of distortion. The density of randomly silenced sections can be modulated to control the amount of noise.

Distortion

2014-07-19T09:40:39Z

Cacofono:

Distortion

2014-07-18T08:34:39Z

Cacofono: Created page with "<div style="font-family: serif; text-transform: capitalize;"> Distortion can refer to a variety of mathematically distinct effects, referring to an aesthetic associated with w..."

Decimation

2014-07-18T04:09:39Z

Cacofono: Created page with "Decimation is an effect in digital signal processing where the sample rate is reduced. Bitcrushing is a similar effect that reduces the bit depth of the signal. Decimation cr..."

Decimation is an effect in digital signal processing where the sample rate is reduced. Bitcrushing is a similar effect that reduces the bit depth of the signal.

Decimation creates crunchy sounds with ringing artifacts, especially if the sampling frequency is at an audible rate (below 20kHz). Bitcrushing, best noticeable when crushed to four bits or less, adds more subtle ringing effects. Crushing to one bit is very, very harsh and identical to extreme clip distortion.

Feedback

2014-07-17T00:17:40Z

Cacofono:

feedback is wrong

see [[Feedback loop]]

feedback happens when a system's output influences a system's input, like when you point a mic at a speaker with the right kind of system, this creates an effect known as chaos, where the slightest disturbance can have a major impact on the system's behavior the result can be very complex and unpredictable

[[Category:Feedback]]

Bowed Strings

2014-07-17T00:08:49Z

Cacofono: Created page with "Violins, violas, cellos, basses. Extreme bow pressure can be used to create harsh, grindy tones. They can also be bowed near the bridge for a thin, ringy timbre, or behind th..."

Violins, violas, cellos, basses.

Extreme bow pressure can be used to create harsh, grindy tones. They can also be bowed near the bridge for a thin, ringy timbre, or behind the bridge for abrasive and squeaky sounds. If the bow is well-rosined, violins and violas can be bowed (with a lot of force) on the tailpiece as well for a low-pitched noise. Percussive sounds can be created via snap pizzicato or by tapping on the instrument's body. Hard objects, as well as the bow's stick, may also be rapped or ground against the string.

Electric variants of the instruments can of course be plugged in to effects units.

Inspiration: Krzysztof Penderecki's ''Threnody to the Victims of Hiroshima'' for string orchestra, George Crumb's ''Black Angels'' for amplified quartet

Brown Noise

2014-07-16T23:47:06Z

Cacofono:

[[Image:Brown-noise.gif]]

Brown noise is not be confused with a brown note even though either might come from your butt.

Its power spectrum density is inversely proportional to the square of the frequency, so it sounds somewhat natural thanks to the inverse-square law. Even worse than [[Pink Noise]].

[[category:Noise Styles]]

Pink Noise

2014-07-16T23:43:39Z

Cacofono:

'''Pink noise''' is made by people who are too much of a pussy to make [[Harsh Noise|harsh]], manly noise... like the trve noize warriors [[Manowar]]. So instead they resort to half-assed noise which isn't even loud unless you turn up the volume on your stereo. Which needless to say is a huge no-no.

Its frequency distribution is set up so that the power spectrum density is inversely proportional to the frequency. It is a softer hiss than [[White Noise]], and more pleasant to the human ear. Fuck that shit.

[[category:Noise Styles]]

White Noise

2014-07-16T23:37:21Z

Cacofono:

[[Image:Whitenoise.jpg]]

What you get after a TV station is blown up.

Mathematically speaking, white noise is about as simple as it gets. It is a random signal with a constant power spectral density. With a finite sample rate, it can be approximated using random amplitudes over a uniform distribution. Sonically, it is best described as a hiss. Loud or long-duration white noise can be obnoxious and slightly painful, which isn't a bad thing depending on the artistic context.

[[category:Noise Styles]]