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Re: Oval and round windows

Perhaps the oval shape is simply a means to reduce the mass of the stapes footplate (and the associated mass loading of the perilymph in the vestibule). Keeping the mass small would allow better high-frequency hearing. I'm not sure if reducing a round to an oval shape makes a substantial mass difference (considering the other masses in the ossicular chain), but this is my best immediate guess at a simple reason for the oval shape.

The round window's main function is for pressure relief, so you want the membrane to be as compliant as possible (for good low-frequency hearing), which I'm pretty sure is achieved with a round shape. Again, this is just a guess at a simple explanation.


Erik Larsen
Eaton-Peabody Laboratory of Auditory Physiology
Massachusettts Eye & Ear Infirmary
243 Charles St
Boston MA 02114

Lawrence Borden wrote:
Hello Folks,

Although it is probably a simple question for most of you, I have not run
across an answer to a question that occurred to me while gazing at the
lovely structure of the middle ear. Can anyone offer an explanation as to
why one window is oval while the other is round? Is there some additional
mechanical advantage to differing shapes?

Lawrence Borden
Vanderbilt University