Much work on avian audition has been done by Bob Dooling at Univ. Maryland.
( see www|bsos.umd.edu/PSYC/DOOLING/intro.htm) His behavioral audiometry
work confirms that few of his song birds tested hear much above ~6kHz.
Nonetheless some birds have rich tones in their vocalizations that are above
10kHz, so I would not rule out the possibility that these birds might also
perceive sound in these higher frequencies. While hearing in these higher
frequencies might not be supported by a "hair cell count," there may be
other ways that birds can discriminate signals in a shorter time domain than
the frequency limitations would indicate.
While human sound perception is typically limited to 20 - 17kHz (or so) we
can discriminate time domain information well up to 20uSec. (1/50kHz). We
use this information to inform us about our surroundings and warn us about
changes to our surroundings that may prove pernicious. It could stand to
reason that while certain birds may not be able to discriminate pitches in
the realm of the Nyctalus vocalization range, that their prey species might
have evolved some hearing sensitivities or sound processing to avoid
In a related framing; unlike humans that have only 3 types of cones in our
eyes - roughly translating to red, green and blue sensitivities, many birds
have 4 types of cones. This may account for a visual acuity that we would
not have the vocabulary to describe.
It's great to know that we have much more to learn.
Ocean Conservation Research
On Behalf Of Hough, Gerald
Sent: Wednesday, March 19, 2008 8:38 AM
Subject: RE: Songbirds audiogram.
The earlier works of J.C. Saunders (and I recall Manley and Gleich too)
might be helpful resources as well for finding information regarding the
perceptual limit of bird hearing...
I believe that the top perceptual limit for most bird hearing was around 8.5
kHz (from an older Saunders review article). When I was doing a pilot
project (never completed) on high-frequency phase-locking ability of n.
magno neurons in zebra finch (with Sue Volman), I don't recall finding a lot
of scientific evidence of folks actually TESTING this limit in songbirds.
Individual species might have a small number of hair cells/magno cells that
can track sound up to the barn owl limit, I just don't recall people testing
frequencies higher than 2.5 kHz. Regardless, it might not be behaviorally
relevant even if they do.
Of course, the last time I poked my head in that area was in the late 90's,
so advances might have been made in the interim.
Gerald Hough, Ph.D.
Assistant Professor, Dept's Biological Sciences and Psychology Rowan
201 Mullica Hill Rd, Glassboro NJ 08028
On Behalf Of Martin Braun
Sent: Tuesday, March 18, 2008 3:14 PM
Subject: Re: Songbirds audiogram.
your group of bird species is almost certainly totally deaf at >6 kHz. The
only investigated species that is known to have a hearing range of
(slightly) >10 kHz is the barn owl.
For references, you might like to make use of the publications of Geoff
Manley and Christine Köppl.
Neuroscience of Music
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