The "Beaming Frequency" is where curved line‑source behavior strays from straight line‑source behavior. Line arrays are hybrid solutions that exhibit both straight as well as curved line‑source behavior.
The former causes Proportional‑Q — in the vertical plane — whereas the latter Constant‑Q. And there will be an inevitable frequency span where one behavior transitions into the other. During which vertical beamwidth will narrow, by as much as one‑third less than nominal. The frequency where vertical beamwidth is at its narrowest is historically known as the "Beaming Frequency".
Audio practitioners and musicians alike are intimately familiar with slapback echoes when a snare drum's sound bounces off a specular rear wall or balcony face, a phenomenon less frequently observed with kick drum sounds. This discrepancy hints at a frequency‑dependent echo perception‑threshold.
Sound traveling slower through the audience than the air above it, is a well‑accepted phenomenon. And compelling supporting evidence has been published in the past decade. Nevertheless, one must always remain vigilant of the possible causes for sound getting decelerated. Is the audience to blame, or a drop in temperature, or a combination of both?
Kurtosis and crest factor are closely related. But unlike crest factor, Kurtosis is not exclusively peak‑centric. Kurtosis indicates the presence of outliers in general as well as peaks. For music, kurtosis is a function of frequency (Figure 1).
Regrettably, in order to appreciate this, some math is inevitable.
Bill Whitlock and his education on Audio System Grounding and Interfacing.
Whitlock recommends relatively simple means to — methodologically — identify causes for disturbance signals. And while his teachings have always appealed to me, I never got to the point of actually building some of the tools myself. Until recently.