Acoustic lobing

Acoustic lobing refers to the radiation pattern of a combination of two or more loudspeaker drivers at a certain frequency, as seen looking at the speaker from its side. In most multi-way speakers, it is at the crossover frequency that the effects of lobing are of greatest concern, since this determines how well the speaker preserves the tonality of the original recorded content.

In practice, room-effects and interactions largely mean that the ideal loudspeaker (or combination thereof) is not practically possible. However a speaker that has the best dispersion at all frequencies of interest (especially the crossover frequency), will have the least colouration of sound - i.e., it will most faithfully reproduce the recorded material. Thus, an ideal speaker would have no lobes at all frequencies - in other words it will act as a point source radiating omnidirectionally at all frequencies. In practice all speakers will exhibit some amount of lobing at the crossover frequency. The primary reasons for this are the physical distance between the drivers, and the drivers' effective diameters relative to the frequency of interest.