Audio amplifier with protection against acoustic feedback - uses adaptive filter in electrical feedback loop

摘要

Acoustic positive feedback (15) in the space (2) between a sound transducer (3), e.g. a microphone, and a loudspeaker (7), can cause problems of distortion, or in severe cases, of high-pitched oscillation. The detected sound (S) is fed via an adding circuit (13) via an amplifier (8) to a loudspeaker (7). The amplifier output (9) is also fed (10), via an adaptive transversal filter (HF), to the neagive input of the adding circuit. The filter (HF) provides electrical negative feedback which balances the acoustic positive feedback.