**Question:** A young man presents with an accident leading to loss of hearing in right ear. On otoscopic examination the tympanic membrane was intact. Pure tone audiometry shows an Air-Bone gap of 55 dB in the right with normal cochlear reserve. Which of the following will be the likely tympanometry finding -

A. Type A
B. Type B
C. Type C
D. Type D

**Correct Answer:** D. Type D

**Core Concept:**

Tympanometry is a non-invasive test used to evaluate the eardrum (tympanic membrane) and the middle ear structure and function. It measures the pressure in the middle ear relative to atmospheric pressure while applying sound waves. The test results are classified into four types based on the shape of the pressure-volume curve: Type A, B, C, and D.

**Why the Correct Answer is Right:**

In this scenario, the patient has a loss of hearing in the right ear due to an accident, and the tympanic membrane appears intact on otoscopic examination. The pure tone audiometry shows an Air-Bone gap of 55 dB in the right ear, indicating a conductive hearing loss. A conductive hearing loss is usually associated with a middle ear pathology. In this case, the normal cochlear reserve suggests that the problem is not in the inner ear or auditory nerve but rather in the middle ear structures.

**Why Each Wrong Option is Incorrect:**

A. Type A: This type of curve is seen in a normal middle ear with intact eardrum and normal middle ear pressure. In our case, the patient has a conductive hearing loss, not a normal eardrum or middle ear pressure.

B. Type B: This type is seen in a middle ear effusion, which is not the case in this scenario.

C. Type C: This type is associated with a normal eardrum but abnormal middle ear pressure, which is not consistent with the patient's clinical presentation.

D. Type D: This type is seen in a middle ear effusion, which is consistent with the patient's conductive hearing loss. The presence of a conductive hearing loss and intact eardrum indicates that the problem lies within the middle ear structures, causing an air-bone gap. Tympanometry Type D (normal pressure and a conductive hearing loss) is a suitable description for this patient's condition.

**Clinical Pearl:**

When assessing a patient with conductive hearing loss, consider performing tympanometry to differentiate between conductive and sensorineural hearing loss. Type D tympanometry is expected in a middle ear effusion (fluid) causing conductive hearing loss, as seen in our patient. This test helps to identify the site of the hearing loss, which in this case is in the middle ear structures.