Noise estimation for speech reinforcement in the presence of strong echoes

Abstract

In announcement and communication systems, clean speech is often played back by loudspeakers in the presence of local background noise which decreases intelligibility. Speech reinforcement is a technique that enhances the intelligibility by adaptively filtering the speech, usually based on measured noise characteristics. In this contribution, solutions known from literature are applied to the case of public address systems where the microphone for noise measurement and the loudspeaker are close to each other and are far away from the listener on the ground. After establishing an acoustical model, the main problems are identified to be strong echoes between loudspeaker and microphone which make conventional noise estimation impossible and lead to an unstable system. A new approach including echo path estimation and echo-aware noise estimation is proposed and evaluated by means of simulations.