In Bing test, on alternately compressing and releasing the external acoustic meatus, the sound increases, and decreases. This indicates
**Core Concept**
The Bing test is a clinical examination used to assess the mobility of the tympanic membrane and the middle ear system. It depends on the principle of impedance matching between the middle ear system and the external ear canal. The test evaluates the tympanic membrane's ability to move in response to changes in air pressure.
**Why the Correct Answer is Right**
When the external acoustic meatus is compressed, the air pressure in the ear canal increases, which pushes the tympanic membrane inward. As a result, the sound intensity decreases due to the increased impedance. Conversely, when the external acoustic meatus is released, the air pressure in the ear canal decreases, allowing the tympanic membrane to move outward, and the sound intensity increases. This phenomenon is observed in cases where the middle ear system is functioning normally.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it does not accurately describe the Bing test's results. The sound intensity does not remain constant in a normal middle ear system.
**Option B:** This option is incorrect because it is too vague and does not provide a specific explanation for the observed phenomenon in the Bing test.
**Option C:** This option is incorrect because it does not relate to the Bing test's results. The ossicular chain's integrity is not directly assessed by this test.
**Clinical Pearl / High-Yield Fact**
The Bing test is a simple yet effective way to assess the mobility of the tympanic membrane and the middle ear system. It is an essential tool in the diagnosis of middle ear problems, such as otosclerosis or middle ear effusions.
**Correct Answer: A. Normal tympanic membrane mobility and middle ear function.**