By: Tony Hoover, FASA, INCE Bd. Cert., MCH Principal
Traditional loudspeakers are tilted toward the audience, but digital processing can "steer" the direction of sound coverage by adjusting the output from individual loudspeakers in column arrays. An advantage is that the columns are more easily hidden or integrated into architectural design, but there can be some problems.
Two column loudspeakers are shown, both consisting of six small individual loudspeakers, each generating a spherical (circular) wavefront, ideally combining into an overall flat wavefront (red line).
Steering the combined wavefront downward is performed by slightly delaying the time at which each successively-lower loudspeaker generates its sound. However, in reality, the results are much more complicated, generating "lobes" of sound rather than a flat wavefront.
The combined wavefront actually takes on a more-complicated shape, as lobes of sound (rather than a flat wavefront). More lobe indicates more sound in a particular direction.
Lobes will change their shape and orientation, and additional side lobes might be generated, depending on the steering and on the frequencies of the sound.
Some side lobes might send sound energy in undesirable directions, which could create echoes or feedback.
Steerable column loudspeakers offer many advantages if they are carefully designed and properly adjusted.