The purpose of this thread is to present horn design regimens that employ “shape optimization” technologies to improve the performance of acoustical horns. It is my conjecture that once shape alternatives have been fully explored using such methods, a new family of scalable horns will emerge from the effort. I also suspect that use of an acoustic lens will reappear as part of an enhanced solution. Numerous papers are available on the Internet that addresses this subject. A few of them are listed here for reader convenience. It is hoped that others will contribute to this initial submission.