title: Low frequency eardrum directionality in the barn owl induced by sound transmission through the interaural canal.
abstract: The middle ears of birds are typically connected by interaural cavities that form a cranial canal. Eardrums coupled in this manner may function as pressure difference receivers rather than pressure receivers. Hereby, the eardrum vibrations become inherently directional. The barn owl also has a large interaural canal, but its role in barn owl hearing and specifically in sound localization has been controversial so far. We discuss here existing data and the role of the interaural canal in this species and add a new dataset obtained by laser Doppler vibrometry in a free-field setting. Significant sound transmission across the interaural canal occurred at low frequencies. The sound transmission induces considerable eardrum directionality in a narrow band from 1.5 to 3.5 kHz. This is below the frequency range used by the barn owl for locating prey, but may conceivably be used for locating conspecific callers.
authors.affiliation: Department of Biology, Center for Comparative and Evolutionary Biology of Hearing, University of Maryland College Park, College Park, MD, 20742, USA. lkettler@umd.edu.|Department of Zoology and Animal Physiology, Institute of Biology II, RWTH Aachen, Worringerweg 3, 52074, Aachen, Germany. lkettler@umd.edu.
authors.forename: Lutz
authors.initials: L
authors.lastname: Kettler
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Christensen-Dalsgaard
authors.affiliation: Department of Biology, University of Southern Denmark, Campusvej 55, 5230, Odense M, Denmark.
authors.forename: Ole Næsbye
authors.initials: ON
authors.lastname: Larsen
authors.affiliation: Department of Zoology and Animal Physiology, Institute of Biology II, RWTH Aachen, Worringerweg 3, 52074, Aachen, Germany.
authors.forename: Hermann
authors.initials: H
authors.lastname: Wagner
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D006309:Hearing / Q000502:physiology*; D011312:Pressure; D013017:Sound Localization / Q000502:physiology*; D020305:Strigiformes / Q000033:anatomy & histology* / Q000502:physiology*; D014432:Tympanic Membrane / Q000502:physiology*
keywords: Auditory; Barn owl; Hearing; Interaural canal; Pressure difference receiver; Sound localization