Biomaterial Database

Middle-ear mechanics in the CF-bat Rhinolophus ferrumequinum. 1983

J P Wilson, and V Bruns

The acoustic vibrations of the eardrum at the umbo and of the stapes have been measured in the greater horseshoe bat. The displacement amplitude response of the eardrum shows a second-order low-pass characteristic, typical of a lumped mass and stiffness system with a resonance frequency of about 55 kHz. The effective mass was calculated to be about 8 micrograms, and the specific stiffness 40 X 10(6) dyne/cm3, which is one hundred times greater than guinea pig. The measured level ratio appears to be greater (3X - 5X) than the geometric ratio (2X) probably due to flexing of the manubrium. The umbo-stapes phase lag exceeds 1 cycle at high frequencies, suggesting a system of at least four reactances. This is not consistent with the relatively slight change in lever ratio with frequency. One possibility for reconciling the two results is that the distributed mass and stiffness of the ossicles act as a transmission line for transverse vibrations. There is no evidence for a sharply peaked middle-ear response (although it is more sharply tuned than some species), nor for resonant absorption by the cochlea in the region of 83 kHz - the 'constant' frequency of this bat. The eardrum shows theoretically optimal matching to the air at 55 kHz and is reasonably efficient from 15 kHz to at least 110 kHz.

UI	MeSH Term	Description	Entries
D002685	Chiroptera	Order of mammals whose members are adapted for flight. It includes bats, flying foxes, and fruit bats.	Bats,Flying Foxes,Horseshoe Bats,Pteropodidae,Pteropus,Rhinolophus,Rousettus,Bat, Horseshoe,Bats, Horseshoe,Foxes, Flying,Horseshoe Bat
D004429	Ear Ossicles	A mobile chain of three small bones (INCUS; MALLEUS; STAPES) in the TYMPANIC CAVITY between the TYMPANIC MEMBRANE and the oval window on the wall of INNER EAR. Sound waves are converted to vibration by the tympanic membrane then transmitted via these ear ossicles to the inner ear.	Auditory Ossicles,Auditory Ossicle,Ear Ossicle,Ossicle, Auditory,Ossicle, Ear,Ossicles, Auditory,Ossicles, Ear
D004432	Ear, Middle	The space and structures directly internal to the TYMPANIC MEMBRANE and external to the inner ear (LABYRINTH). Its major components include the AUDITORY OSSICLES and the EUSTACHIAN TUBE that connects the cavity of middle ear (tympanic cavity) to the upper part of the throat.	Tympanic Cavity,Tympanum,Middle Ear,Cavities, Tympanic,Cavity, Tympanic,Ears, Middle,Middle Ears,Tympanic Cavities,Tympanums
D004455	Echolocation	An auditory orientation mechanism involving the emission of high frequency sounds which are reflected back to the emitter (animal).	Echolocations
D000161	Acoustic Stimulation	Use of sound to elicit a response in the nervous system.	Auditory Stimulation,Stimulation, Acoustic,Stimulation, Auditory
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D001696	Biomechanical Phenomena	The properties, processes, and behavior of biological systems under the action of mechanical forces.	Biomechanics,Kinematics,Biomechanic Phenomena,Mechanobiological Phenomena,Biomechanic,Biomechanic Phenomenas,Phenomena, Biomechanic,Phenomena, Biomechanical,Phenomena, Mechanobiological,Phenomenas, Biomechanic
D013199	Stapes	One of the three ossicles of the middle ear. It transmits sound vibrations from the INCUS to the internal ear (Ear, Internal see LABYRINTH).
D014432	Tympanic Membrane	An oval semitransparent membrane separating the external EAR CANAL from the tympanic cavity (EAR, MIDDLE). It contains three layers: the skin of the external ear canal; the core of radially and circularly arranged collagen fibers; and the MUCOSA of the middle ear.	Eardrum,Eardrums,Membrane, Tympanic,Membranes, Tympanic,Tympanic Membranes
D014732	Vibration	A continuing periodic change in displacement with respect to a fixed reference. (McGraw-Hill Dictionary of Scientific and Technical Terms, 6th ed)	Vibrations