الفهرس 
Anatomy and PhysiologyOnly 14 pages are availabe for public view
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Abstract
Summary
The tympanic membrane (TM) is an important part of the auditory system, which acts as the transmitter of the sound waves from the external ear to the middle ear as it serves as a key component of the tympano-ossicular system for sound transmission. TM also subserves a protective function to the middle ear cleft and round window niche
Perforations of the tympanic membrane (TM) is common in otologic practice and can result from trauma and middle-ear disease
Perforations of the TM can result in a conductive hearing loss (CHL) that ranges from negligible to 50 dBHL.
The larger the size of perforation the higher the degree of hearing loss.
However, there are different opinions about the effect of the location (site) of the perforation on the degree of hearing loss.
So in this study we investigated the effect of site of TM perforation on the degree of conductive hearing loss in dry perforation as follow:
1- 353 ears were enrolled in this study and were collected from the outpatient clinic in the hearing and speech institute and were diagnosed as dry perforation then they have been audiologicaly assessed.
2- Perforated right ears and left ears are nearly equal in number
3- Perforated ears which belong to male patients are 152 ear while perforated ears which belong to female patients are 201 ear
4- Out of 353 ears, 112 (31.7 %) had antero-inferior perforation, 40 (11.3 %) had antero-superior perforation, 119 (33.8 %) had postero-inferior perforation and 82 (23.2 %) had postero-superior perforation.
5- There was significant difference between all sites as regard hearing loss at all frequencies (500 Hz, 1000 Hz, 2000 Hz, 4000 Hz) and also for the mean ABG (p < 0.05)
6- Statistically significant relation is observed between site of perforation and degree of hearing loss; posterior placed perforations seem to have larger air-bone gap.
7- The hearing loss (mean ABG) varied with the site of perforation, being greatest at the postero-superior perforation (28.19 dBHL) and least at antero-inferior perforation (20.97 dBHL) while it was (27.54 dbHL) at postero-inferior and (22.28 dbHL) at antero-superior perforation.
8- The hearing loss was greater in lower frequencies as compared to the higher frequencies irrespective of the site of the perforation.
9- ABG at frequency 500 Hz is more affected than other frequencies
10- ABG was greatest at the postero-superior site while the least ABG was at the antero-inferior site
Conclusion
1- Statistically significant relation is observed between site of T.M. perforation and degree of hearing loss (the mean ABG); posterior placed perforations seem to have larger air-bone gap.
2- There was significant difference between all sites of perforation and degree of hearing loss at all frequencies (500 Hz, 1000 Hz, 2000 Hz, 4000 Hz).
3- The hearing loss was greater in lower frequencies as compared to the higher frequencies irrespective of the site of perforation.