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Updated: Jul 17, 2026

Morphological and Functional Evaluation of Ribbon Synapses at Specific Frequency Regions of the Mouse Cochlea
Published on: May 10, 2019
High-frequency hearing in phocid and otariid pinnipeds: an interpretation based on inertial and cochlear constraints
Simo Hemilä1, Sirpa Nummela, Annalisa Berta
1Department of Biological and Environmental Sciences, University of Helsinki, Helsinki, Finland. snummela@fastmail.fm
Abstract:
Audiograms in air and underwater, determined by previous workers for four pinniped species, two eared seals (Otariidae) and two phocids (Phocidae), are supplemented here by measurements on their middle ear ossicular mass, enabling mechanistic interpretations of high-frequency hearing and audiogram differences. Otariid hearing is not largely affected by the medium (air/water). This indicates that cochlear constraints limit high-frequency hearing in otariids. Phocids, however, have massive middle ear ossicles, and underwater hearing has radically shifted towards higher frequencies. This suggests that the high-frequency hearing of phocids in air is constrained by ossicle inertia.
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