Adaptive feedback cancellation is a common method of cancelling acoustic feedback in a variety of electro-acoustic systems. The time varying acoustic feedback leakage paths can only be eliminated with adaptive feedback cancellation. When an electro-acoustic system with an adaptive feedback canceller is presented with a correlated input signal, a recurrent distortion artifact,Entrainment is generated. The problem of Entrainment known for decades as coloration artifact, bias, and low-frequency artifact in the electro-acoustic industry, has been attributed to a correlated input signal, although the cause had not been identified. This book unifies previous approaches to solving the Entrainment problem and discusses their limited effectiveness. Introduces four novel non Entraining feedback canceller algorithms.