Design of far-field and near-field broadband beamformers using eigenfilters

This paper discusses two novel non-iterative design procedures based on eigenfilters for designing broadband beamformers with an arbitrary spatial directivity pattern for an arbitrary microphone configuration. In the conventional eigenfilter technique a reference frequency-angle point is required, whereas in the eigenfilter technique based on a TLS (Total Least Squares) error criterion, no reference point is required. It is shown how to design broadband beamformers in the far-field, near-field and mixed near-field far-field of the microphone array. Both eigenfilter techniques are compared with other broadband beamformer design procedures (least-squares, maximum energy array, non-linear criterion). It will be shown by simulations that among the considered non-iterative design procedures the TLS eigenfilter technique has the best performance, i.e. best resembling the performance of the non-linear design procedure but having a significantly lower computational complexity.