title: Acoustic-induced motion of the bushcricket (Mecopoda elongata, Tettigoniidae) tympanum.
abstract: Bushcrickets have a tonotopically organised hearing organ, the so-called crista acustica, in the tibia of the forelegs. This organ responds to a frequency range of about 5-80 kHz and lies behind the anterior tympanum on top of a trachea branch. We analyzed the sound-induced vibration pattern of the anterior tympanum, using a Laser-Doppler-Vibrometer Scanning microscope system, in order to identify frequency-dependent amplitude and phase of displacement. The vibration pattern evoked by a frequency sweep (4-79 kHz) showed an amplitude maximum which would correspond to the resonance frequency of an open tube system. At higher frequencies of about 30 kHz a difference in the amplitude and phase response between the distal and the proximal part of the tympanum was detected. The inner plate of the tympanum starts to wobble at this frequency. This higher mode in the motion pattern is not explained by purely acoustic characteristics of the tracheal space below the tympanum but may depend on the mechanical impedance of the tympanum plate. In accordance with a previous hypothesis, the tympanum moves over the whole tested frequency range in the dorso-ventral direction like a hinged flap with the largest displacement in its ventral part and no higher modes of vibration.
authors.affiliation: Department of Cell Biology and Neuroscience, AK Neurobiology and Biosensors, Goethe University Frankfurt am Main, Siesmayerstrasse 70 A, 60323, Frankfurt am Main, Germany. nowotny@bio.uni-frankfurt.de
authors.forename: Manuela
authors.initials: M
authors.lastname: Nowotny
authors.forename: Jennifer
authors.initials: J
authors.lastname: Hummel
authors.forename: Melanie
authors.initials: M
authors.lastname: Weber
authors.forename: Doreen
authors.initials: D
authors.lastname: Möckel
authors.forename: Manfred
authors.initials: M
authors.lastname: Kössl
mesh_terms: D000161:Acoustic Stimulation / Q000379:methods; D000162:Acoustics; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D004432:Ear, Middle / Q000502:physiology* / Q000648:ultrastructure; D005260:Female; D005552:Forelimb / Q000502:physiology* / Q000648:ultrastructure; D006135:Gryllidae / Q000502:physiology* / Q000648:ultrastructure; D006309:Hearing / Q000502:physiology*; D008297:Male; D013045:Species Specificity; D014732:Vibration; D014828:Vocalization, Animal / Q000502:physiology
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