Takes care of the hi-freq keen eared animals except at slow/no wind.
Still think we Gots to come up with an outside sound source, which also IDs what-sort of Thing is approaching;
the other animals won't decode that, but they'll hear.. even when the sucker is silently creeping along
(maybe re birds, while they are concentrating on the road-kill? and about to be squashed in slo-mo.)


Nothing's entirely simple..