You are here

Florida Manatee (Trichechus Manatus Latirostris) Outer and Middle Ear Morphology

Title: Florida Manatee (Trichechus Manatus Latirostris) Outer and Middle Ear Morphology: Potential Sound Conduction Pathways and Middle-Ear Mechanism.
198 views
33 downloads
Name(s): Chapla, Marie E., author
Nowacek, Douglas P., professor directing thesis
Rommel, Sentiel A., outside committee member
Huettel, Markus, committee member
Laurent, Louis St., committee member
Department of Earth, Ocean and Atmospheric Sciences, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2006
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The Florida manatee (Trichechus manatus latirostris) is an obligate aquatic mammal that inhabits shallow coastal waterways. Previous research has demonstrated that manatees vocalize using frequencies that range from < 0.5 kHz to 12 kHz (Frisch and Frisch, 2003; Nowacek et al., 2003) and hear frequencies between 0.4 kHz and 45 kHz (Bullock et al., 1982; Gerstein et al., 1999). Although the auditory anatomy has been described previously (Fischer, 1988; Ketten et al., 1992; Chapla and Rommel, 2003), potential sound pathways and middle ear mechanisms have not been analyzed. In the current study, Computerized Tomography (CT) is utilized to generate three-dimensional reconstructions of manatee heads and isolated earbone (tympanoperiotic) complexes in order to visualize the in situ arrangement of soft tissue and bone. Density data attached to the CT data are used to make calculations regarding the transmission and reflection of sound waves, with varying angles of incidence, as they encounter the boundaries of different tissue layers. Sound waves with 90° angles of incidence (relative to the tissue/water interface) will transmit 94% to 99% of their total energy intensity to the skull. Sound waves approaching at oblique angles to the surface of the head will transmit less of their energy intensity. The fraction of energy intensity in the transmitted wave will decrease with a decrease in the angle of incidence. Additional calculations of critical angles and an isospeed channel suggest that the inner fatty tissue layer (bounded by muscle and bone) does not provide an efficient channel for sound waves. Other potential sound pathways are discussed. A model of inertial bone conduction predicts that the peak displacement amplitude of the stapes, relative to that of the head, will be 8.4 dB at 200 Hz, and that inertial bone conduction may be possible between 125 Hz and 1000 Hz. Comparisons are made with data from humans and golden moles (Mason, 2003).
Identifier: FSU_migr_etd-3888-P (IID)
Submitted Note: A Thesis submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Master of Science.
Degree Awarded: Spring Semester, 2006.
Date of Defense: April 7, 2006.
Keywords: Middle Ear Anatomy, Three-Dimensional Reconstruction, Manatee Hearing, Inertial Bone Conduction
Bibliography Note: Includes bibliographical references.
Advisory Committee: Douglas P. Nowacek, Professor Directing Thesis; Sentiel A. Rommel, Outside Committee Member; Markus Huettel, Committee Member; Louis St. Laurent, Committee Member.
Subject(s): Oceanography
Atmospheric sciences
Meteorology
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_etd-3888-P
Owner Institution: FSU

Choose the citation style.
Chapla, M. E. (2006). Florida Manatee (Trichechus Manatus Latirostris) Outer and Middle Ear Morphology: Potential Sound Conduction Pathways and Middle-Ear Mechanism. Retrieved from http://purl.flvc.org/fsu/fd/FSU_migr_etd-3888-P

Title: Florida Manatee (Trichechus Manatus Latirostris) Outer and Middle Ear Morphology: Potential Sound Conduction Pathways and Middle-Ear Mechanism.
Name(s): Chapla, Marie E., author
Nowacek, Douglas P., professor directing thesis
Rommel, Sentiel A., outside committee member
Huettel, Markus, committee member
Laurent, Louis St., committee member
Department of Earth, Ocean and Atmospheric Sciences, degree granting department
Florida State University, degree granting institution
Type of Resource: text
Genre: Text
Issuance: monographic
Date Issued: 2006
Publisher: Florida State University
Place of Publication: Tallahassee, Florida
Physical Form: computer
online resource
Extent: 1 online resource
Language(s): English
Abstract/Description: The Florida manatee (Trichechus manatus latirostris) is an obligate aquatic mammal that inhabits shallow coastal waterways. Previous research has demonstrated that manatees vocalize using frequencies that range from < 0.5 kHz to 12 kHz (Frisch and Frisch, 2003; Nowacek et al., 2003) and hear frequencies between 0.4 kHz and 45 kHz (Bullock et al., 1982; Gerstein et al., 1999). Although the auditory anatomy has been described previously (Fischer, 1988; Ketten et al., 1992; Chapla and Rommel, 2003), potential sound pathways and middle ear mechanisms have not been analyzed. In the current study, Computerized Tomography (CT) is utilized to generate three-dimensional reconstructions of manatee heads and isolated earbone (tympanoperiotic) complexes in order to visualize the in situ arrangement of soft tissue and bone. Density data attached to the CT data are used to make calculations regarding the transmission and reflection of sound waves, with varying angles of incidence, as they encounter the boundaries of different tissue layers. Sound waves with 90° angles of incidence (relative to the tissue/water interface) will transmit 94% to 99% of their total energy intensity to the skull. Sound waves approaching at oblique angles to the surface of the head will transmit less of their energy intensity. The fraction of energy intensity in the transmitted wave will decrease with a decrease in the angle of incidence. Additional calculations of critical angles and an isospeed channel suggest that the inner fatty tissue layer (bounded by muscle and bone) does not provide an efficient channel for sound waves. Other potential sound pathways are discussed. A model of inertial bone conduction predicts that the peak displacement amplitude of the stapes, relative to that of the head, will be 8.4 dB at 200 Hz, and that inertial bone conduction may be possible between 125 Hz and 1000 Hz. Comparisons are made with data from humans and golden moles (Mason, 2003).
Identifier: FSU_migr_etd-3888 (IID)
Submitted Note: A Thesis submitted to the Department of Oceanography in partial fulfillment of the requirements for the degree of Master of Science.
Degree Awarded: Spring Semester, 2006.
Date of Defense: April 7, 2006.
Keywords: Middle Ear Anatomy, Three-Dimensional Reconstruction, Manatee Hearing, Inertial Bone Conduction
Bibliography Note: Includes bibliographical references.
Advisory Committee: Douglas P. Nowacek, Professor Directing Thesis; Sentiel A. Rommel, Outside Committee Member; Markus Huettel, Committee Member; Louis St. Laurent, Committee Member.
Subject(s): Oceanography
Atmospheric sciences
Meteorology
Persistent Link to This Record: http://purl.flvc.org/fsu/fd/FSU_migr_etd-3888
Owner Institution: FSU