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The '''zero-crossing rate''' is the rate of sign-changes along a [[signal (information theory)|signal]], i.e., the rate at which the signal changes from positive to negative or back.<ref>* Chen, C. H., Signal processing handbook, Dekker, New York, 1988</ref> This feature has been used heavily in both [[speech recognition]] and [[music information retrieval]], being a key feature to classify percussive sounds.<ref>Gouyon F., Pachet F., Delerue O. (2000),[http://www.csl.sony.fr/downloads/papers/2000/gouyon-dafx2000.pdf Classifying percussive sounds: a matter of zero-crossing rate?], in Proceedings of the COST G-6 Conference on Digital Audio Effects (DAFX-00), Verona, Italy, December 7–9, 2000. Accessed 26th April 2011.</ref> | |||
ZCR is defined formally as | |||
:<math>zcr = \frac{1}{T-1} \sum_{t=1}^{T-1} {{\mathbb I}\left\{{s_t s_{t-1} < 0}\right\}}</math> | |||
where <math>s</math> is a signal of length <math>T</math> and the indicator function <math>{{\mathbb I}\left\{{A}\right\}}</math> is 1 if its argument <math>A</math> is true and 0 otherwise. | |||
In some cases only the "positive-going" or "negative-going" crossings are counted, rather than all the crossings - since, logically, between a pair of adjacent positive zero-crossings there must be one and only one negative zero-crossing. | |||
For [[Monaural|monophonic]] tonal signals, the zero-crossing rate can be used as a primitive [[pitch detection algorithm]]. | |||
==Applications== | |||
Zero crossing rates are used for [[Voice activity detection]](VAD), i.e., finding whether a segment of speech is voiced or unvoiced. | |||
==See also== | |||
* [[Zero crossing]] | |||
* [[Digital signal processing]] | |||
==References== | |||
<references /> | |||
[[Category:Signal processing]] | |||
{{Signal-processing-stub}} | |||
Revision as of 04:44, 7 April 2013
The zero-crossing rate is the rate of sign-changes along a signal, i.e., the rate at which the signal changes from positive to negative or back.[1] This feature has been used heavily in both speech recognition and music information retrieval, being a key feature to classify percussive sounds.[2]
ZCR is defined formally as
where is a signal of length and the indicator function is 1 if its argument is true and 0 otherwise.
In some cases only the "positive-going" or "negative-going" crossings are counted, rather than all the crossings - since, logically, between a pair of adjacent positive zero-crossings there must be one and only one negative zero-crossing.
For monophonic tonal signals, the zero-crossing rate can be used as a primitive pitch detection algorithm.
Applications
Zero crossing rates are used for Voice activity detection(VAD), i.e., finding whether a segment of speech is voiced or unvoiced.
See also
References
- ↑ * Chen, C. H., Signal processing handbook, Dekker, New York, 1988
- ↑ Gouyon F., Pachet F., Delerue O. (2000),Classifying percussive sounds: a matter of zero-crossing rate?, in Proceedings of the COST G-6 Conference on Digital Audio Effects (DAFX-00), Verona, Italy, December 7–9, 2000. Accessed 26th April 2011.