Polyphase Filter Bank Implementation of a Linear-Phase Octave Graphic Audio Equalizer

Bruschi V, Cecchi S. Polyphase Filter Bank Implementation of a Linear-Phase Octave Graphic Audio Equalizer. J Audio Eng Soc. 2026;74(7/8):524-532. doi:10.17743/jaes.2026.0274

@article{Bruschi2026_23393,
  author = {Bruschi, Valeria and Cecchi, Stefania},
  title = {{Polyphase Filter Bank Implementation of a Linear-Phase Octave Graphic Audio Equalizer}},
  journal = {Journal of the Audio Engineering Society},
  volume = {74},
  number = {7/8},
  pages = {524--532},
  year = {2026},
  month = jul,
  publisher = {Audio Engineering Society},
  doi = {10.17743/jaes.2026.0274},
  url = {https://doi.org/10.17743/jaes.2026.0274}
}

TY  - JOUR
TI  - Polyphase Filter Bank Implementation of a Linear-Phase Octave Graphic Audio Equalizer
AU  - Bruschi, Valeria
AU  - Cecchi, Stefania
T2  - Journal of the Audio Engineering Society
J2  - J. Audio Eng. Soc.
VL  - 74
IS  - 7/8
SP  - 524
EP  - 532
PY  - 2026
DA  - 2026/07/20
DO  - 10.17743/jaes.2026.0274
UR  - https://doi.org/10.17743/jaes.2026.0274
PB  - Audio Engineering Society
LA  - en
AB  - An efficient implementation of an octave-band linear-phase graphic equalizer (GEQ) based on a polyphase filter bank is presented. The method builds on a previous multirate structure that employs dual filter banks and intermediate cross-terms to prevent aliasing in each transition band. Extending this approach, a ten-octave-band GEQ is designed with analysis and synthesis filter banks derived from a single prototype filter and a binary tree structure. The key enhancement lies in employing filters of varying lengths and utilizing a polyphase representation, which enables processing at a lower rate and reduces computational load without compromising the linear phase response. The performance of the proposed GEQ is evaluated and compared with other linear phase GEQs. The results demonstrate that it achieves a 97.2% reduction in the number of operations compared with the previous multirate method and a 0.59 dB decrease in error relative to an efficient GEQ based on interpolated filters. These improvements highlight the effectiveness of the polyphase-based approach in balancing computational efficiency and magnitude response accuracy, making it an effective solution for high-quality audio equalization.
ER  -