You might find the Springer Handbook of Auditory Research, Volume 46 (2013) "The Middle Ear: Science, Otosurgery, and Technology", edited by S.Puria, R.R. Fay and A.N. Popper useful. For example in the chapter by J. Rosowski, it says:

"Unlike other vertebrates the mammalian TM has two components, the central pars tensa and the more posterior-dorsal pars flaccida (Shrapnell 1832; Funnell and Laszlo 1982; Kohllo¨ffel 1984). As the names imply, the pars tensa is generally stiffer and less deformable than the pars flaccida, whose shape is easily altered by small static pressure differences on either side of the membrane (Decraemer and Dirckx 1998; Dirckx et al. 1998). Indeed the pars flaccida is often assumed to play a role in maintaining equal static pressures on either side of the TM: It is thought to buffer small changes in middle ear volume produced by the absorption or generation

of middle ear gas by and from the blood (Hellstrom and Stenfors 1983; Sade´ et al. 1996; Decraemer and Dirckx 1998). Further, although only the pars tensa is directly coupled to the ossicular chain, it has been suggested that the pars flaccida, whose motions appear independent of the pars tensa, plays a role in equalizing lowfrequency sound pressures across the pars tensa, thereby indirectly reducing the motion of the pars tensa in response to low-frequency sounds (Kohllo¨ ffel 1984; Teoh et al. 1997).

The book contains many comments and data on Pars flaccida.

Geoff Manley

Thank you very much for the information Sir.

Nice question and answer.. Thank you

Is there any soft copy of this book which you could share ?

Unfortunately the whole series "Springer Handbook of Auditory Research" is only available as hardback or as pdf files online - the latter for each chapter separately. You can always try writing to each author...

Okay, thank you so much sir !

Very informative answer. Thank you all

Very good question and an informative answer. Thanks.

Thank you very much. Please share your valuable inputs and queries.

Perhaps we should challenge the pressure-dampening theory.

WIth many cases, the pars flaccida is small or virtually absent, without discernible disadvantage re pressure effects. Can anyone remember/feel/notice these cases to have problems?

Also, with pressure changes, small pars tends shifts would easily outmatch the pars flaccid volume effect?