Zhiyun Li Ramani Duraiswami Flexible and Optimal Design of Spherical Microphone Arrays for Beamforming. 702-714 2007 15 IEEE Transactions on Audio, Speech & Language Processing 2 http://dx.doi.org/10.1109/TASL.2006.876764 db/journals/taslp/taslp15.html#LiD07