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.
Click to purchase paper as a non-member or you can login as an AES member to see more options.
No AES members have commented on this paper yet.
To be notified of new comments on this paper you can
subscribe to this RSS feed.
Forum users should login to see additional options.
If you are not yet an AES member and have something important to say about this paper then we urge you to join the AES today and make your voice heard. You can join online today by clicking here.
