On Thu, Jan 19, 2006 at 08:12:40AM +1100, Evan Beaver wrote:
> Can humans hear the echo-location
> noises of bats? Is it not too high, out of our frequency range?
Most bat echolocation calls are beyond human hearing range - some have
little energy below 100khz, far beyond our upper limit of ~20khz.
But as you mention there are exceptions. Some White-Striped Mastiff
(Freetail) Bat echolocation calls are well within human hearing range.
They are one of the more common night sounds around Sydney during warmer
months. I'd describe the call as a high-pitched click - similar to
some katydid calls.
In areas with high street lights you can sometimes spot the bat making
the calls. You can also hear the repetition rate of calls rapidly
increase as the bat homes in on prey and once-or-twice I reckon I've
heard an insect being crunched shortly afterwards.
Ghost Bats are another bat that makes regular calls in flight
with an audible component - not sure if they are echolocation calls.
And somewhere I have recordings I made near Maningrida of an interesting
warbled audible call made in flight by bats. I haven't heard it anywhere
else and I have no clue what the species is.
Can't guess what Bob Gosford's nocturnal caller is though.
Andrew
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