Conventional column loudspeakers provide no significant horizontal directivity below 2 kHz due to their physical size. At low and mid frequencies, the resulting polar pattern is almost omni-directional as shown by the dotted line in the Free field horizontal polar plot illustration. The continuous line shows the cardioid pattern of the 16C with reduced radiation to the rear of the loudspeaker.
Typically, column loudspeakers are mounted onto walls or other hard plane surfaces which act as an acoustic mirror, as shown in the Wall mounted horizontal polar plot illustration. This results in the room not only being covered by the sound of the actual column loudspeaker, but also by the sound produced by its virtual mirror source from behind. In the case of conventional column loudspeakers, the mirror source radiates at a similar level as the loudspeaker itself. The combination of both sources results in a dipolar characteristic where the main energy is radiated along the walls as indicated by the dotted line. With their cardioid dispersion patterns, when similarly wall mounted, the 16C provides an even dispersion characteristic and useful directivity, as shown by the continuous line in the Wall mounted horizontal polar plot.