[Mike Rivers]

bill wrote:
The speaker did kind of roll off the
birds but I could hear trucks and trains for miles, even farther than
with my own ears. A 4" speaker does seem to be kind of optimum around
200-400 Hz.

A local sound company built some long throw (very directional) horn
cabinetss, and to test them out, pointed them off the back deck of
their building, across a field, and out to a major highway, a distance
of about a quarter of a mile. Someone from the company drove down the
highway while they were playing music through the speakers to get an
idea of the directivity pattern. Then they got the idea to hook one up
to a mixer mic input (this was before anyone had "mic preamps") and
listen to what they were picking up. They could hear radios in the cars
going by.