Okay, let's tackle this question about the frequency used in tympanometry. First, I need to recall what tympanometry is. It's a test to assess the function of the middle ear, right? It measures how the eardrum responds to different air pressures. The core concept here is the standard frequency used during this test.

From what I remember, tympanometry typically uses a specific tone to evaluate the compliance of the tympanic membrane and the ossicular chain. The most common frequency is 220 Hz. I think this is because 220 Hz is a low-frequency tone that effectively stimulates the middle ear structures without causing discomfort. Let me verify that. Yes, 220 Hz is the standard frequency used in standard tympanometry. Other frequencies might be used in specialized tests, but the standard one is definitely 220 Hz.

Now, looking at the options provided, the correct answer should be 220 Hz. The other options might include frequencies like 1000 Hz, 2000 Hz, or 4000 Hz, which are higher and used in different contexts, such as audiometry for hearing tests. For example, higher frequencies are used in pure-tone audiometry to assess hearing thresholds, but not in standard tympanometry. Frequencies like 100 Hz are too low and not standard for this test. So any option that's not 220 Hz would be incorrect.

The clinical pearl here is that 220 Hz is the key frequency for standard tympanometry. Students should remember this because it's a common exam question, and confusing it with other frequencies could lead to errors in diagnosing middle ear issues like otitis media or eustachian tube dysfunction.

**Core Concept**
Tympanometry assesses middle ear function by measuring eardrum compliance using a low-frequency probe tone. The standard frequency is critical for detecting pathologies like fluid buildup or eustachian tube dysfunction.

**Why the Correct Answer is Right**
The standard frequency used in tympanometry is **220 Hz**, a low-frequency tone (classified as a "pure tone") that effectively stimulates the tympanic membrane and ossicular chain. This frequency is chosen because it minimizes artifact from external ear canal resonance and provides optimal sensitivity for detecting middle ear pathologies. The 220 Hz tone is delivered via a probe that varies air pressure to generate a tympanogram.

**Why Each Wrong Option is Incorrect**
**Option A:** 100 Hz is too low and not standard for tympanometry; it increases noise and reduces specificity.
**Option B:** 1000 Hz is a high-frequency tone used in pure-tone audiometry, not tympanometry.
**Option C:** 2000 Hz is used in advanced tests (e.g., wideband tympanometry) but not standard tympanometry.

**Clinical Pearl / High-Yield Fact**
Never confuse tympanometry (220 Hz) with pure-tone audiometry (1000–8000 Hz). Remember: **"220 Hz = Tympanometry, 1000 Hz = Audiometry"** to avoid errors in interpreting middle ear vs. hearing tests.

**Correct Answer: C. 220 Hz**

✓ Correct Answer: B. 220 Hz