Dear All, 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 predation. 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. Regards, Michael Stocker Ocean Conservation Research -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Hough, Gerald Sent: Wednesday, March 19, 2008 8:38 AM To: [email protected] Subject: RE: Songbirds audiogram. Hi folks, 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 ======================== Gerald Hough, Ph.D. Assistant Professor, Dept's Biological Sciences and Psychology Rowan University 201 Mullica Hill Rd, Glassboro NJ 08028 ======================== -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Martin Braun Sent: Tuesday, March 18, 2008 3:14 PM To: [email protected] Subject: Re: Songbirds audiogram. Dear Jean-Francois, 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. Martin --------------------------------------------------------------------- Martin Braun Neuroscience of Music S-671 95 Klässbol Sweden web site: http://w1.570.telia.com/~u57011259/index.htm ----- Original Message ----- From: "Jean-Francois Julien" <[EMAIL PROTECTED]> To: <[email protected]> Sent: Tuesday, March 18, 2008 3:12 PM Subject: Songbirds audiogram. We are currently working on the echolocation of a bird- AND insect-eating bat, Nyctalus lasiopterus. That bat emits shallow FM calls over a wider range than other Nyctalus species. Frequency of max energy varies from 12 to 17 kHz. Although many things remain unclear, the lowest frequency (12 to 13 kHz) calls are emitted in circumstances where we believe that bats are foraging for birds rather than for insects. Conversely, higher frequency (15 to 17 kHz) search sequences were recorded in areas and seasons where potential insect prey was abundant. From a physical point of view, the lowest frequency calls should be more efficient in detecting large and distant objects. However, they could be much more conspicuous to birds. I have been unable to find clear and general data about bird auditory sensitivity. Species of interest belong mainly to the genera Erithacus, Phylloscopus, Sylvia etc. Does somebody here know if the auditory sensitivity of those species drops significantly more between 12 and 15 kHz than between, e.g., 10 and 12 kHz? Thanks a lot for your answer(s), Jean-Francois Julien Centre de Genetique Moleculaire C.N.R.S. 1, avenue de la Terrasse F-91190 Gif sur Yvette phone: 33 1 69823226 fax: 33 1 69823160 cel.phone: 33 6 68049987 No virus found in this incoming message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.21.7/1331 - Release Date: 3/16/2008 10:34 AM No virus found in this outgoing message. Checked by AVG Free Edition. Version: 7.5.516 / Virus Database: 269.21.7/1331 - Release Date: 3/16/2008 10:34 AM
