Multi-channel audio recording based on superdirective beamforming for portable multimedia recording devices

In this paper, an audio recording method using a near-coincident microphone array is proposed for a multichannel audio system. A coincident or near-coincident microphone recording method attempts to capture spatial images in a multi-channel audio system depending on directional-level differences or directivities. Thus, high directivity is required for good spatial quality in the multichannel audio system, and it is usually obtained using a directional microphone. However, the currently available microphones such as cardioid, hyper-cardioid, and figure-8 directional microphones have lower directivities. To overcome this problem, the proposed method forms a superdirective sound beam in each steered direction using closely spaced omni-microphones. It is shown from subjective listening tests that the proposed method provides higher spatial quality with lower timbral distortions than other conventional recording methods for stereo and 5.1-channel audio systems.