Design of a howling suppression circuit based on chopping

Howling is a significant problem in most audio amplifier systems with microphones, adversely affects speech intelligibility. In this paper, a method for suppression of howling noise is proposed, based on choppers using low-cost analog multiplexers. The method applies the design of single power supply and has the advantages of lowering the cost and increasing efficiency of the circuit. In addition, the method is optimized by modulating the inhibitory effect. Results show that, the optimal amount of frequency shift is about 10Hz, which adapts to howling noise with little degradation of sound quality.