Two-channel signal detection and speech enhancement based on the transient beam-to-reference ratio

In reverberant and noisy environments, multichannel systems are designed for spatially filtering interfering signals coming from undesired directions. In case of incoherent or diffuse noise fields, beamforming alone does not provide sufficient noise reduction, and post-filtering is normally required. In this paper, we present a two-channel post-filtering approach for signal detection and speech enhancement. A mild assumption is made, that a desired signal component is stronger at the beamformer output than at the reference noise signal, and a noise component is stronger at the reference signal. The ratio between the transient power at the beamformer output and the transient power at the reference noise signal is used for indicating whether such a transient is desired or interfering. Experimental results demonstrate the usefulness of the proposed approach in a car environment.