Hello all,
I believe that ventriloquism is something that is perceived by the
individual (as a sound that appears to come from somewhere other than
the source) and may be perceived differently by different individuals.
The problem with the discussion so far has been the intended audience
of the call - who, or what, is the call intended for?
A territorial or advertisement call of a given species is probably
only intended for others of that species, within a certain distance or
neighbourhood. It will be in a frequency range and timescale
detectable and useful for that species and purpose. The fact that we
can hear it is somewhat of a byproduct.
To accurately compare what these species 'hear' compared with us, we
would have to shrink (or expand) our heads and change the structures
of our ears to that of the species under inspection. Alternatively, we
could make a recorder that does something similar. Perhaps a stereo
microphone with the two elements spaced at the width of the animals
head (rather than our head with) could be used to detect the phase
differences of the call, and hence the direction. Some bird calls have
elements that happen too quickly for us to perceive them, such as fast
buzzes and whistles, so we may have to slow the recordings down to
appreciate their complexity. Additionally, the frequencies we hear
will be different to those that can be detected by other animals, so
relevant filtering may have to be done.
The use of a single direction mic, such as a parabolic dish or shotgun
mic, would be able to detect the direction of the strongest signal,
which would be the one of least resistance (from attenuation by
foliage or landforms). This is usually the direct line-of-sight but
very occasionally can be some sort of reflection.
I have heard this phenomena on a few occasions in Australian animals.
Like Syd's original message, with the incredibly strong and peircing
calls of Scrub Birds. Red-lored Whistler can make a buzzing sound
which is nearly impossibly to locate at close range. Similarly for
Red-eared and Beautiful Firetails. One frog (Taudactylus liemi) that I
can distinctly remember trying to track down sounded like it was 20
metres away on a large boulder when it was actually nearly under my foot!
Sorry if this was a bit of a rant, but I find the perception of sounds
produced by animals very interesting. This is my first post to the
group, so thank you for having me.
Alistair Stewart
Melbourne
Australia
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