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ISSN 2522-9028 (Print)
ISSN 2522-9036 (Online)

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 foramens and dolphin hearing

Riabov VO

    Karadag Natural Reserve of NAS of Ukraine, Ukraine


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


  1. Babushina E.S. Zvukovaya retseptsiya morskih mlekopitayushchih v zavisimosti ot parametrov i putei provedeniya zvuka . Biofizika. 1999. 44, Vip. 6. S. 1101-1108.
  3. Ryabov V.A. Osobennosti akusticheskogo polya meshayushchih otrazhenii i eholokatsionnii sluh del'fina . Biofizika. " 2008. " 53, Vip.3. " S. 504-512.
  5. Ryabov V.A. A dolphin lower jaw is a hydroacoustic antenna of the traveling wave . J. Acoust. Soc. Amer. 2003. 114, 4. P. 2414-2415. CrossRef  
  6. Ryabov V.A. Lower jaw peripheric part of the dolphin echolocation hearing. Moscow: KMK, 2004. P. 483-489.
  8. Ryabov V.A. Mechanisms of a dolphin's echolocation hearing. Bio-Acoustics, 2007. (Fourth Int. Conf. on Bio-Acoustics, Loughborough University, UK) . Proc. Institute Acoustics. 2007. 29. Pt. 3. P. 283-293.
  10. Bullock T.H., Grinell A.D., Ikezono E., Kameda K., Katsuki J., Nomota M., Sato O., Suga N., Yanagisawa K. Electrophysiological studies of central auditory mechanisms in cetaceans . Z. Vergl. Physiol. " 1968. 59. P. 117-156.
  12. Brill R.L., Moore P.W.B., Helweg D.A., Dankiewicz L.A. Investigating the dolphin's peripheral hearing system: acoustic sensitivity about the head and lower jaw . Tehnical report 1865. 2001. P. 1-14. CrossRef  
  13. Johnson C.S. Sound detection thresholds in marine mammals . Oxford: Pergamon Press, 1967. P. 247-260 .
  15. Johnson C.S. Maskes tonal thresholds in the bottlenose porpoise . J. Acoust. Soc. Amer. 1968. 44, 4. P. 965-967. CrossRef PubMed
  17. Hemila S., Nummela S., Reuter T. A model of the odontocete middle ear . Her. Res. 1999. 133. P. 82-97. CrossRef  
  18. Koopman H.N., Budge S.M., Ketten D.R., Iverson S.J. Topographical distribution of lipids inside the mandibular fat bodies of Odontocetes: Remarkable complexity and consistency . J. Ocean. Engin. 2006. 31,1. P. 95-106. CrossRef  
  19. Goodson A.D., Klinowska M. A proposed echoloca­tion receptor for the bottlenose dolphin (Tursiops truncatus): Modeling the received directivity from tooth and lower jaw geometry . Eds. J.A. Thomas, R.A. Kastelein. Sensory abilities of cetaceans: Laboratory and field evidence. New York: Plenum Press, 1990. P. 255-269. CrossRef  
  20. Mshhl B., Au W.W.L., Pawloski J., Nachtigall P.E. Dolphin hearing: Relative sensitivity as a function of point of application of a contact sound source in the jaw and head region . J. Acoust. Soc. Amer. 1999. 105. P. 3421-3424. CrossRef PubMed
  22. McCormick J.G., Wever E.G., Palin J., Ridgway S.H. Sound conduction in the dolphin ear . J. Acoust. Soc. Amer. 1970. 48, 6 (part 2). P. 1418-1428. CrossRef PubMed
  24. Norris K.S. Some problems of echolocation in ceta­ceans . W. Tavolga. Marine bio-Acoustics. New York: Pergamon press, 1964. P. 316-336.
  26. Norris K.S. The evolution of acoustic mechanisms in odontocete cetaceans . New Haven. Lond: Jail Univ. Press, 1968. P. 297-324.
  28. Potter, J.R., Taylor, E.A. On novel reception models for bottlenose dolphin echolocation . Proc. IOA. 2001. 23. Pt. 4. P. 103-112.
  30. Schusterman R.J. Behavioral methodology in echoloca­tion by marine mammals . Animal sonar systems. New York: Plenum Publishing Corp., 1980. P. 11-41. CrossRef  

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