@conference{harrell1989an, title = {An Array Filtering Implementation of a Constant Beamwidth Acoustic Source}, author = {Harrell, Jefferson A. and Hixson, Elmer L.}, booktitle = {Audio Engineering Society Convention 87}, month = {Oct}, year = {1989}, url = {https://www.aes.org/e-lib/browse.cfm?elib=5849} }