Any disease process which interferes with the conduction of sound to reach cochlea causes conductive hearing loss.
The lesion can lie in any of the following areas;
- External ear
- Typmanic membrane
- Middle ear
- Ossicles upto stapediovestibular joint
Characteristics:
The characteristics of conductive hearing loss are;
- Negative Rinne teat i.e.BC>AC
- Weber lateralized to poorer ear
- Normal absolute bone conduction
- Low frequencies affected more
- Speech discrimination is good
- Loss is not more than 60dB
Aetiology:
The cause may be congenital or acquired:
Congenital causes:
- Meatal atresia
- Fixation of stapes footplate
- Fixation of malleus head
- Ossicular discontinuity
Acquired causes:
- Obstruction of ear canal
- Perforation of tympanic membrane
- Fluid in middle ear
- Mass in middle ear
- Fixation of ossicles
