Zero-crossing rate

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 zero to negative or from negative to zero to positive.[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 is an indicator function.

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 human speech is present in an audio segment or not.

gollark: Fascinating and yet apiological.
gollark: Incorrect. PotatOS is inevitable.
gollark: Yes, due to EXTREMELY high atmospheric bee levels.
gollark: Specifically, apiocontracognitoforms.
gollark: Well, as they say, "ignorance is bees".

See also

References

    • Chen, C. H., Signal processing handbook, Dekker, New York, 1988
  1. Gouyon F., Pachet F., Delerue O. (2000),On the Use of Zero-crossing Rate for an Application of Classification of Percussive Sounds, in Proceedings of the COST G-6 Conference on Digital Audio Effects (DAFX-00 - DAFX-06), Verona, Italy, December 7–9, 2000. Accessed 26 April 2011.


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