Dan Jacobson wrote:

The situation: neighbors have installed a public address system with
two 16 ohm 60 watt speakers to keep monkeys from eating their crops.

How should one go about adding more speakers to this with the goal of
diffusing the sound? I.e., several smaller sources spread out, instead
of few larger sources. Assume the P.A. system is locked in a black
box, and all we can do is add things to the system, or else they might
get angry. Yes, I could easily replace the big speakers with many
small speakers with total ohms matching, but alas the big speakers
must still be a part of the system lest tempers flare.

http://www.bcae1.com/spkrmlti.htm warns that just hooking more
speakers in parallel can ruin an amplifier. But P.A. systems are not
the usual amplifier? Also perhaps the system will try to compensate
for the increased load: the original two speakers will continue at
their original levels?

Other rural noise: http://jidanni.org/me/quiet_en.html

Shoot the monkeys and stuff thier carcasses in the horns of the
offending speakers.

I have heard of this being tried with barnyard animals and after a while
they become accustomed to the noise and come back.