**Core Concept**
Middle ear deafness, also known as conductive hearing loss, occurs due to a problem in the middle ear that prevents sound from being conducted to the inner ear. The primary issue lies in the transmission of sound through the ossicles (malleus, incus, and stapes) or the eardrum.

**Why the Correct Answer is Right**
The correct test for diagnosing middle ear deafness is tympanometry. Tympanometry measures the movement of the eardrum and the reflexes of the middle ear muscles. It is a non-invasive test that helps in assessing the mobility of the eardrum and the middle ear reflexes. This test is especially useful in diagnosing middle ear problems such as otitis media, eustachian tube dysfunction, and ossicular chain disruption.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because audiometry, while useful in assessing hearing loss, does not specifically diagnose middle ear problems. It can only indicate the type and severity of hearing loss.
**Option B:** This option is incorrect because acoustic reflex testing, although useful in assessing middle ear reflexes, is not a comprehensive test for diagnosing middle ear deafness.
**Option C:** This option is incorrect because pure tone audiometry is a type of audiometry that measures the threshold of hearing for different frequencies, but it does not specifically diagnose middle ear problems.

**Clinical Pearl / High-Yield Fact**
Middle ear deafness can be caused by various factors, including otitis media, eustachian tube dysfunction, and ossicular chain disruption. Tympanometry is a valuable tool in diagnosing these conditions and guiding further management.

**Correct Answer: D. Tympanometry**