A 25 year old woman suffering from bilateral hearing loss for 6 year which became profound with pregnancy. On tympanogram which of the following curve is obtained

Ans. is 'b' i.e. As Bilateral painless hearing loss in 25 yr. old female accentuated with pregnancy is suggestive of otosclerosis or otospongiosis Tympanometry shows As curve due to ossicular stiffness.TympanometryIs based on the principle of reflection of sound energywhen sound strikes tympanic membrane, some of the sound energy is absorbed while the rest is reflected.A stiffer tympanic membrane would reflect more of sound energy than a compliant one.By changing the pressures in a sealed external auditory canal and then measuring the reflected sound energy, it is possible to find the compliance or stiffness of the Tympano-ossicular system and thus find the healthy or diseased status of the middle ear.By charting the compliance of Tympano-ossicular system against various pressure changes, different types of graphs called tympanogram are obtained.These Tympano grams are diagnostic of certain middle ear pathologies.Types of tvmpanogramsType ANormal tympanogramType AsReduced compliance at or near ambient air pressure. Seen in fixation of ossicles, eg. otosclerosis or malleus fixation.Type AdIncreased compliance at or near ambient pressure. Seen in ossicular discontinuity or thin and lax tympanic membrane.Type BFlat or dome shaped graph. Seen in middle ear fluid or thick tympanic membrane.Type CMaximum compliance at pressures more than -100 mm H2O (negative pressure in middle ear) eg. eustachian tube obstruction or early stage of serous otitis media.