GULP,  well as my wife says the excellent hearing (detection of
vibrations) that I had as a youth has become selective. Did I hear
something or just think I heard it?  I must claim victim status ,
overtaken by a the english language where a word doesn't really mean what
it means. Obviously bees hear or detect vibrations as in thumping the
hive, or when a top is popped off when stuck tight. Now about this
ultrasound device to run off pests, I called one of the manufacturers and
had a good discussion with them,  their contention is that  the
frequencies used irritate the nervous systems of target vermin and
insects and causes them to find a more suitable (less annoying) place to
live.  Next time I must remember to be more careful about my choice of
words.
Sorry for the confusion, but had a great time reading where it led.
Al Boehm,    Columbus N C