NEMATODES

taxonomy, morphology and phylogeny

Reverse Transmission along the Ossicular Chain in Gerbil

Publication Type:Journal Article
Year of Publication:2012
Authors:W. Dong, Decraemer, W. F., Olson, E. S.
Journal:Jaro-Journal of the Association for Research in OtolaryngologyJaro-Journal of the Association for Research in Otolaryngology
Volume:13
Pagination:447-459
Date Published:Aug
ISBN Number:1525-3961
Accession Number:WOS:000305910200002
Abstract:

In a healthy cochlea stimulated with two tones f (1) and f (2), combination tones are generated by the cochlea's active process and its associated nonlinearity. These distortion tones travel "in reverse" through the middle ear. They can be detected with a sensitive microphone in the ear canal (EC) and are known as distortion product otoacoustic emissions. Comparisons of ossicular velocity and EC pressure responses at distortion product frequencies allowed us to evaluate the middle ear transmission in the reverse direction along the ossicular chain. In the current study, the gerbil ear was stimulated with two equal-intensity tones with fixed f (2)/f (1) ratio of 1.05 or 1.25. The middle ear ossicles were accessed through an opening of the pars flaccida, and their motion was measured in the direction in line with the stapes piston-like motion using a laser interferometer. When referencing the ossicular motion to EC pressure, an additional amplitude loss was found in reverse transmission compared to the gain in forward transmission, similar to previous findings relating intracochlear and EC pressure. In contrast, sound transmission along the ossicular chain was quite similar in forward and reverse directions. The difference in middle ear transmission in forward and reverse directions is most likely due to the different load impedances-the cochlea in forward transmission and the EC in reverse transmission.

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