Audio processing in police investigations

Auteurs-es

  • 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.

Mots-clés :

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

Résumé

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.

Fichiers supplémentaires

Publié-e

2004-09-01

Comment citer

1.
Luknowsky D, Boyczuk J. Audio processing in police investigations. Canadian Acoustics [Internet]. 1 sept. 2004 [cité 14 mai 2026];32(3):154-5. Disponible à: https://jcaa.caa-aca.ca/index.php/jcaa/article/view/1674

Numéro

Vol. 32 No. 3 (2004)

Rubrique

Actes du congrès de la Semaine canadienne d'acoustique

Licence

Author Licensing Addendum

This Licensing Addendum ("Addendum") is entered into between the undersigned Author(s) and Canadian Acoustics journal published by the Canadian Acoustical Association (hereinafter referred to as the "Publisher"). The Author(s) and the Publisher agree as follows:

  1. Retained Rights: The Author(s) retain(s) the following rights:

    • The right to reproduce, distribute, and publicly display the Work on the Author's personal website or the website of the Author's institution.
    • The right to use the Work in the Author's teaching activities and presentations.
    • The right to include the Work in a compilation for the Author's personal use, not for sale.

  2. Grant of License: The Author(s) grant(s) to the Publisher a worldwide exclusive license to publish, reproduce, distribute, and display the Work in Canadian Acoustics and any other formats and media deemed appropriate by the Publisher.

  3. Attribution: The Publisher agrees to include proper attribution to the Author(s) in all publications and reproductions of the Work.

  4. No Conflict: This Addendum is intended to be in harmony with, and not in conflict with, the terms and conditions of the original agreement entered into between the Author(s) and the Publisher.

  5. Copyright Clause: Copyright on articles is held by the Author(s). The corresponding Author has the right to grant on behalf of all Authors and does grant on behalf of all Authors, a worldwide exclusive license to the Publisher and its licensees in perpetuity, in all forms, formats, and media (whether known now or created in the future), including but not limited to the rights to publish, reproduce, distribute, display, store, translate, create adaptations, reprints, include within collections, and create summaries, extracts, and/or abstracts of the Contribution.