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  • Research Article
  • Open Access

Equalization of Loudspeaker and Room Responses Using Kautz Filters: Direct Least Squares Design

EURASIP Journal on Advances in Signal Processing20062007:060949

https://doi.org/10.1155/2007/60949

  • Received: 30 April 2006
  • Accepted: 16 July 2006
  • Published:

Abstract

DSP-based correction of loudspeaker and room responses is becoming an important part of improving sound reproduction. Such response equalization (EQ) is based on using a digital filter in cascade with the reproduction channel to counteract the response errors introduced by loudspeakers and room acoustics. Several FIR and IIR filter design techniques have been proposed for equalization purposes. In this paper we investigate Kautz filters, an interesting class of IIR filters, from the point of view of direct least squares EQ design. Kautz filters can be seen as generalizations of FIR filters and their frequency-warped counterparts. They provide a flexible means to obtain desired frequency resolution behavior, which allows low filter orders even for complex corrections. Kautz filters have also the desirable property to avoid inverting dips in transfer function to sharp and long-ringing resonances in the equalizer. Furthermore, the direct least squares design is applicable to nonminimum-phase EQ design and allows using a desired target response. The proposed method is demonstrated by case examples with measured and synthetic loudspeaker and room responses.

Keywords

  • Digital Filter
  • Filter Design
  • Target Response
  • Filter Order
  • Room Acoustics

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Authors’ Affiliations

(1)
Department of Electrical and Communications Engineering, Laboratory of Acoustics and Audio Signal Processing, Helsinki University of Technology, P.O. Box 3000, FI, 02015, Finland

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Copyright

© M. Karjalainen and T. Paatero. 2007

This article is published under license to BioMed Central Ltd. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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