Computer Simulations of Periodically Time-Varying Filters for Acoustic Feedback Control

Svensson PU. Computer Simulations of Periodically Time-Varying Filters for Acoustic Feedback Control. J Audio Eng Soc. 1995;43(9):667-677. Available from: https://aes.org/publications/elibrary-page/?id=7932

@article{Svensson1995_7932,
  author = {Svensson, Peter U.},
  title = {{Computer Simulations of Periodically Time-Varying Filters for Acoustic Feedback Control}},
  journal = {Journal of the Audio Engineering Society},
  volume = {43},
  number = {9},
  pages = {667--677},
  year = {1995},
  month = sep,
  publisher = {Audio Engineering Society},
  url = {https://aes.org/publications/elibrary-page/?id=7932}
}

TY  - JOUR
TI  - Computer Simulations of Periodically Time-Varying Filters for Acoustic Feedback Control
AU  - Svensson, Peter U.
T2  - Journal of the Audio Engineering Society
J2  - J. Audio Eng. Soc.
VL  - 43
IS  - 9
SP  - 667
EP  - 677
PY  - 1995
DA  - 1995/09/06
UR  - https://aes.org/publications/elibrary-page/?id=7932
PB  - Audio Engineering Society
LA  - en
AB  - Several modern systems for reverberation enhancement use time-varying electronic filters to increase their gain before instability (GBI). A computer simulation study is presented of systems with linear periodically time-varying (LPTV) filters based on an iterative frequency-domain method. Results are given from simulations and measurements of a single feedback loop with phase and delay modulators and feedback via an electronic reverberation unit. Comparison of measured and predicted values of GBI with a sinusoidal phase modulator showed deviations typically around 0.1 dB and at most 0.3 dB for modulation frequencies between 0.5 and 4 Hz and modulation indexes of up to 4.2 radians. Phase modulators displayed GBI improvements increasing almost monotonically with a modulation index up to 4.2 radians. Delay modulators gave slight improvement when used broad band, but when high-pass filtered at 600-Hz substantial improvements resulted with variations as low as ±0.5 ms. The detrimental effects of modulation in the form of audible amplitude and frequency fluctuations were studied as well.
ER  -