[Mental foramens and dolphin hearing].
Detection thresholds of short broadband acoustic impulses with an energy maximum on frequencies 8, 16, 30 and 100 kHz was measured in the dolphin (Tursiops truncatus p.) with using techniques of behavioral responses in the indoor pool. At acoustic shielding of mental foramens, detection thresholds of these impulses worsen on 30, 34, 40 and 50 dB, respectively. The new original results obtained experimentally prove that mental foramens are the unique sound-conducting pathway for sounds of about 6-160 kHz frequency band (in consideration of stimulus broadbandness). In this connection the assumption that morphological structures of the lower jaw represent a specialized peripheral part of the dolphin hearing, which was based on studying of morphology and results of modelling, receives additional experimental confirmation. The mental foramens play part of external auditory canals and conduct all frequency range of the hearing of dolphin into fat body of the mandibular canal. Via fat body sounds transmit to a lateral side of an acoustical bone and into the middle and inner ear. From morphology similarity, it is possible to assume presence of the similar sound-conducting mechanism in Odontoceti.
Riabov
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D000161:Acoustic Stimulation; D000273:Adipose Tissue / Q000502:physiology; D000818:Animals; D001306:Auditory Pathways / Q000033:anatomy & histology / Q000502:physiology*; D001309:Auditory Threshold / Q000502:physiology*; D050681:Bottle-Nosed Dolphin / Q000033:anatomy & histology / Q000502:physiology*; D006309:Hearing / Q000502:physiology*; D008334:Mandible / Q000033:anatomy & histology / Q000502:physiology*; D010470:Perceptual Masking