7565998
Description
Flashcards by Lara Hiles, updated more than 1 year ago
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Created by Lara Hiles
over 7 years ago
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| Question | Answer |
| Purpose of avian auditory system | Used for hearing and balance |
| Three parts of ear | (1) External ear (2) Middle ear (3) Inner ear |
| External ear | Has no pinna -> open tube ends in tympanum (eardrum) |
| Middle ear | Only made up of a single bone called the columella |
| Columella | Ossicle of middle ear that conducts sound to oval window |
| Inner ear | Contains three, fluid-filled semicircular canals (one in each plane) and cochlea |
| Cochlea | Curved projection from base of semicircular canals (organ of hearing) |
| Three differences between bird and mammalian cochlea | (1) Curved in birds; coiled in mammals (2) Smaller with more sensory cells per unit length in birds (3) Glandular tegmentum is absent in mammals |
| Glandular tegmentum | Thick, folded membrane that fills cavity above basilar membrane and contains sensory cells Stimulated by sounds at different frequencies which results from variations in stiffness of basilar membrane |
| Oval window | Vibrations of oval window transmit fluid |
| Hertz | Unit of frequency; equal to one cycle per second |
| Sound sensitivity in birds vs. mammals | Birds are most sensitive in ranges of 1-5 Hz (upper limit of 10-12 Hz) Birds have greater sensitivity to low frequency sounds than most mammals Humans are slightly more sensitive than most birds over an entire range |
| Infrasound | Sound waves with frequencies below lower limit of human audibility (long wavelength, low frequency) May be used by birds to determine location of other individuals |
| Measuring Temporal Resolution | (1) Gap threshold (2) Temporal fine structure |
| Gap Threshold | Ability to distinguish two sounds separated by a very short time interval Similar ability between birds and humans |
| Temporal Fine Structure | Ability to detect rapid changes within sounds (varying detail) Ability is much better in birds than in humans -> birds can distinguish between sounds played forwards and backwards by sensing fine temporal differences |
| Specialized Features of Auditory System of Owls | (1) More sensitive to high frequency sounds than other birds of similar size (2) Modification to external ears -> possess operculum (fleshy, erectile flap that concentrates and reflects sound from rear) and asymmetrical ear openings (more sensitive to detecting sounds depending on position of head) (3) Modifications to inner ear and brain -> large eardrums, columella, and cochlea relative to body size; enlarged sensory area in medulla of hindbrain (4) Facial disk -> densely-packed, stiff feathers that collect and focus sound into external auditory opening |
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