Impulse noise is a category of (
acoustic)
noise
Noise is unwanted sound considered unpleasant, loud or disruptive to hearing. From a physics standpoint, there is no distinction between noise and desired sound, as both are vibrations through a medium, such as air or water. The difference arise ...
that includes unwanted, almost instantaneous (thus
impulse
Impulse or Impulsive may refer to:
Science
* Impulse (physics), in mechanics, the change of momentum of an object; the integral of a force with respect to time
* Impulse noise (disambiguation)
* Specific impulse, the change in momentum per uni ...
-like) sharp sounds (like clicks and pops)—typically caused by
electromagnetic interference
Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electros ...
, scratches on disks,
gunfire
A gunshot is a single discharge of a gun, typically a man-portable firearm, producing a visible flash, a powerful and loud shockwave and often chemical gunshot residue. The term can also refer to a ballistic wound caused by such a discharg ...
, explosions, and synchronization issues in digital audio. High levels of such a noise (200+
decibel
The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a po ...
s) may damage internal organs, while 180
decibel
The decibel (symbol: dB) is a relative unit of measurement equal to one tenth of a bel (B). It expresses the ratio of two values of a power or root-power quantity on a logarithmic scale. Two signals whose levels differ by one decibel have a po ...
s are enough to damage human ears.
An impulse noise filter can enhance the quality of noisy signals to achieve robustness in pattern recognition and adaptive control systems. A classic filter used to remove impulse noise is the
median filter
The median filter is a non-linear digital filtering technique, often used to remove noise from an image or signal. Such noise reduction is a typical pre-processing step to improve the results of later processing (for example, edge detection on an ...
, at the expense of signal degradation. Thus it's quite common to get better performing impulse noise filters with model-based systems, which are programmed with the time and frequency properties of the noise to remove only impulse obliterated samples.
See also
*
Audio synchronizer
An audio synchronizer is a variable audio delay used to correct or maintain audio-video sync or timing also known as lip sync error. See for example the specification for audio to video timing given in ATSC Document IS-191. Modern television sys ...
*
Crackling noise
Crackling noise arises when a system is subject to an external force and it responds via events that appear very similar at many different scales. In a classical system there are usually two states, on and off. However, sometimes a state can exis ...
*
Record restoration
Record restoration, a particular kind of audio restoration, is the process of converting the
analog signal stored on gramophone records (either 78 rpm shellac, or 45 and 33⅓ rpm
vinyl) into digital audio files that can then be edited with compu ...
*
Gaussian noise
Gaussian noise, named after Carl Friedrich Gauss, is a term from signal processing theory denoting a kind of signal noise that has a probability density function (pdf) equal to that of the normal distribution (which is also known as the Gaussia ...
References
Noise (electronics)
Acoustics
Sound
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