Anatomy and physics of the exceptional sensitivity of dolphin hearing (Odontoceti: Cetacea).
J Comp Physiol A Neuroethol Sens Neural Behav Physiol
; 196(3): 165-79, 2010 Mar.
Article
em En
| MEDLINE
| ID: mdl-20091313
ABSTRACT
During the past 50 years, the high acoustic sensitivity and the echolocation behavior of dolphins and other small odontocetes have been studied thoroughly. However, understanding has been scarce as to how the dolphin cochlea is stimulated by high frequency echoes, and likewise regarding the ear mechanics affecting dolphin audiograms. The characteristic impedance of mammalian soft tissues is similar to that of water, and thus no radical refractions of sound, nor reflections of sound, can be expected at the water/soft tissue interfaces. Consequently, a sound-collecting terrestrial pinna and an outer ear canal serve little purpose in underwater hearing. Additionally, compared to terrestrial mammals whose middle ear performs an impedance match from air to the cochlea, the impedance match performed by the odontocete middle ear needs to be reversed to perform an opposite match from water to the cochlea. In this paper, we discuss anatomical adaptations of dolphins a lower jaw collecting sound, thus replacing the terrestrial outer ear pinna, and a thin and large tympanic bone plate replacing the tympanic membrane of terrestrial mammals. The paper describes the lower jaw anatomy and hypothetical middle ear mechanisms explaining both the high sensitivity and the converted acoustic impedance match.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Acústica
/
Golfinhos
/
Orelha
/
Audição
Tipo de estudo:
Diagnostic_studies
Limite:
Animals
/
Humans
Idioma:
En
Revista:
J Comp Physiol A Neuroethol Sens Neural Behav Physiol
Assunto da revista:
CIENCIAS DO COMPORTAMENTO
/
NEUROLOGIA
Ano de publicação:
2010
Tipo de documento:
Article
País de afiliação:
Finlândia