Analysis of Additional Stable Gain by Frequency Shifting for Acoustic Feedback Suppression using Statistical Room Acoustics

Currently, a quantitative prediction of the performance of the frequency shifting (FS) approach for stabilizing acoustic feedback loops of public address (PA) systems is only possible in case of negligibly small direct sound components in the feedback path. By employing a statistical room acoustics model, this letter derives a novel analytical expression for the additional stable gain (ASG) with the FS approach. This allows a quantitative prediction of the performance of FS in the presence of significant direct sound components for the first time. Simulation results confirm the theoretical analysis.