When our hearing is normal we can recognize our
name or pick out snatches of conversation in a room where a lot of people are
talking at once. If our hearing has to be digitally supplemented, this is more
difficult to do. If a computer is tasked
with this “dip listening” task, it is very ineffectual. This has become known
as the “cocktail party problem.”
In the current pre-print issue of the Journal of
Animal Behavior, Vélèz and Bee of the U of Minnesota have pondered on
the problem for grey treefrogs who have the problem of fixing up dates amid the
cacophony of their numerous relatives all croaking themselves hoarse.
The
problem they address is are the females able to dip listen effectively so they
can pick out their soul mate calling amongst the very loud chatter of the
general melee of a noisy communal bacchanal.
Well,
our treefrog ladies were somewhat handicapped if their soul mates calls were
done in short bursts. They seemed to lose the sound in the rise and fall of the
noisy background. They did rather better if their suitors were more long winded
and called out about their potential prowess in long bursts with the pulse rate
of the call coming into line with the background fluctuations.
If
things quieted down somewhat, the length of the calls again had to be quite
long if the guys were going to get any traction. So it seems that treefrogs
aren’t very good at dip listening. There again, maybe the girls just want a
clearer statement of intent which doesn’t quite sound like the same old song.
- A. Vélèz and M. A. Bee, doi:10.1016/j.anbehav.2011.09.015
