The line array effect of the narrowing of the beam with increasing frequency was first demonstrated by acoustical pioneer Harry Olson.[5] He published his findings in his 1957 text, Acoustical Engineering.[6] Olson used line array concepts to develop the column speaker in which vertically aligned drivers in a single enclosure produced mid-range output in a wide horizontal and narrow vertical pattern. Line arrays have been around for over half a century but until recently most were voice range only. The application for these were for highly reverberant spaces where a narrow vertical design kept from exciting the reverberant field.[7]