Great colleagues you have, Geoff ;-)
This is amazing technology, It is just unfortunate that they do not use b&o speakers.
These are used in an anechoic chamber, so it’s better to use loudspeakers with flat on-axis magnitude responses. Bang & Olufsen loudspeakers are intentionally not-flat on-axis, since we place a significant amount of attention to the off-axis and power responses of the loudspeaker.
Genelec (whose speakers are shown in the photo) also pay big attention to the off-axis and power responses of the loudspeaker, which all can be found plotted in their user manuals.
You’re correct, of course. (I hope that I did not imply that the opposite was the case…) However, this does not change the fact that they are “tuned” to have a flat on-axis response. The off-axis and power responses are “cleaned up” using things like physical shape, crossover type, and crossover frequency range (among other things, of course).
For example, you can have two loudspeakers that have flat on-axis responses, but very different off-axis and power responses. This is why having nothing but an on-axis response measurement, for a domestic loudspeaker is possibly worse-than-useless… (because you might get seduced into thinking that the loudspeaker is behaving well, and therefore sounding good when its off-axis response is a mess…)
Bang & Olufsen loudspeakers are different in that we not only pay attention to the on-axis, off-axis, and power responses – but we use all three to influence the overall tuning of the loudspeakers. Consequently, no current Bang & Olufsen loudspeaker is flat on-axis in a free field – by design. Of course, we could easily make any of our loudspeakers have a flat on-axis anechoic response by changing the filtering in the DSP – but this would make them sound worse in a normal domestic listening environment.
of course, smooth directivity and power response is in normal listening room reality more important than just flat on axis response and that’s why many Hifi speakers sound so ̶p̶̶o̶̶o̶̶r̶ different although they are relatively flat on 0° axis. But the best way to go is to achieve both flat 0° response AND smooth directivity, angle and power response as this way the speaker sounds neutral also in near field listening conditions and also the imaging is better as the reflected sound correlates better to the direct one. But who am I to tell you this, companies like yours, Harman group and some serious monitoring companies like Genelec all try to perfectionize this in their products. By the way was that your blog that posted these so interesting directivity measurements? https://www.princeton.edu/3D3A/Directivity.html If not very recommendable read.