Years ago, I represented Terra in New England, and I loved the sound. I now live in York Beach, which most Mainers consider a Boston suburb, so as a fake Mainer, I figured I’d chime in on your nicely done article.
My Rep firm is high end, custom, and cinema centric (Barco, Stewart Filmscreen, ACURUS, AcousticSmart, Planar, Vitrea, Torus etc; and now, full disclosure, I also work as a consultant with the James Loudspeaker Company as their Director Architectural Audio Services. So, I’ve been working on some of the same challenges your piece addresses.
The issue you raise regarding inverse square law is fundamental to any good sound system design. I used it in a cinema sound project for JLS in the usual way; speaker sensitivity in 1W/1m terms plus power handling in dB, and then distance calcs to the ‘Reference Listening Position’, or RLP. In outdoor design it’s a little more complicated, especially when using distributed satellite-subwoofer designs. In discrete or 2 channel full range design you have the problem as illustrated, very loud near the speaker with 12 to 24dB level drops in only 2 to 4 distance ‘doublings’, only 16’ away. I prefer higher density distributed channel designs where in the same space two large speakers would cover, we use 8 directional satellites with a couple distributed sub locations. The benefit is that the blending of small sats doesn’t behave exactly like a single point source. I can’t say they behave like a cylindrical wave front, for only a 3dB loss per doubling of distance, but it is similar. It is far less lossy, and of course you get perfectly even coverage within the array. Stereo content always sounds best, and in these configurations we use the L-R-L-R channel assignment method. All of this greatly improves level uniformity over the coverage space, and greatly reduces the adjacent property noise issue.
For outdoor cinema sound we use standard modern indoor design techniques. Conventional direct radiating satellites are used in the surround layer, with matching under eave, trellis, or tree mounts for the elevation speakers. Multiple subs are used for even bass uniformity and intensity. James Loudspeaker even made a full size patio immersive audio pergola in the aluminum channel used for many of their enclosures. It was configured as an ATMOS/AURO compatible array. Specially priced at only $100K!
Do these things and the great outdoors get even greater.
It is a wonderful way to enjoy Maine, most of the time!