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ISSN 2522-9028 (Print)
ISSN 2522-9036 (Online)
DOI: https://doi.org/10.15407/fz

Fiziologichnyi Zhurnal

is a scientific journal issued by the

Bogomoletz Institute of Physiology
National Academy of Sciences of Ukraine

Editor-in-chief: V.F. Sagach

The journal was founded in 1955 as
1955 – 1977 "Fiziolohichnyi zhurnal" (ISSN 0015 – 3311)
1978 – 1993 "Fiziologicheskii zhurnal" (ISSN 0201 – 8489)
1994 – 2016 "Fiziolohichnyi zhurnal" (ISSN 0201 – 8489)
2017 – "Fiziolohichnyi zhurnal" (ISSN 2522-9028)

Fiziol. Zh. 2010; 56(3): 98-103


Mental foramensand dolphin hearing

V.A. Ryabov.

    Карадазьк. природ. заповідник НАН України


Abstract

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 thresholdsof 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.

Keywords: dolphin, hearing, mental foramens, fat body,mandibular canal, sound-conduction

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