Audio processing in police investigations

Authors

  • David Luknowsky Audio and Video Analysis Section, Royal Canadian Mounted Police, Ottawa, Ont.
  • Jeff Boyczuk Audio and Video Analysis Section, Royal Canadian Mounted Police, Ottawa, Ont.

Keywords:

Adaptive filtering, Algorithms, Electric filters, Gain control, Information analysis, Radio interference, Signal processing, Spurious signal noise, Analogue noise, Audio processing, Filter parameters, Frequency noise

Abstract

The various methods applied by the Audio and Video Analysis Section of the Royal Canadian Mounted Police (RCMP) to reduce the interferences and improve the intelligibility of audio recordings are discussed. Hum, a kind of tone which comes from powerlines and fluorescent lights can be removed with a comb filter. A series of individual tones at unequally spaced frequencies or tones whose frequency varies can be solved with the help of an adaptive filter. If tones are strong yet stationary and unevenly spaced, it can be removed with an inverse filter. A spectralinverse filter with shaping provides an amplitude boost to high voice frequencies and shape the spectrum to an averaged voice spectrum.

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Published

2004-09-01

How to Cite

1.
Luknowsky D, Boyczuk J. Audio processing in police investigations. Canadian Acoustics [Internet]. 2004 Sep. 1 [cited 2021 Dec. 7];32(3):154-5. Available from: https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1674

Issue

Section

Proceedings of the Acoustics Week in Canada