Re: Oval and round windows

[Erik Larsen <elarsen@xxxxxxx>]

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

--
Erik Larsen
Eaton-Peabody Laboratory of Auditory Physiology
Massachusettts Eye & Ear Infirmary
243 Charles St
Boston MA 02114
https://research.meei.harvard.edu/epl/index.html

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
> Lawrence.Borden@xxxxxxxxxxxxxx