It is to be expected that variations in the field will account for drop in performance from those measured in a laboratory, significantly worse performance can typically be traced to a failure to follow three simple checks.
A relatively inexpensive hobby of mine is the collecting of old technology books. My collection includes books on rebuilding player pianos, blacksmithing and a mail order course on how to set up a vacuum tube radio repair shop (I will be set if my time machine leaves me stranded in the 1850s or 1950s).
I love it when a plan comes together. Those of you who know me know that I like to push the envelope with my designs. If I can’t find an acoustic treatment that meets my needs, then I’ll design one.
Also called the “coincidence dip” or “critical frequency,” this hole-in-the-wall is the easiest way for noise to travel through most walls; a narrow band-pass at 3000 Hz. Today, a new hole-in-the-wall gang is taking advantage of this natural phenomenon.
