**Core Concept**
Tinnitus is a subjective auditory symptom, but in certain cases, it can be objective, meaning it can be heard by an examiner with a stethoscope. Objective tinnitus is often associated with physical conditions that affect the ear or the auditory system.

**Why the Correct Answer is Right**
Objective tinnitus is typically caused by middle ear muscle contractions, such as in the case of middle ear myoclonus. This condition is characterized by spasmodic contractions of the stapedius or tensor tympani muscles, leading to a palpable thrill and audible sound. The sound is usually a low-frequency humming noise, often described as a "pulsatile tinnitus".

**Why Each Wrong Option is Incorrect**
**Option A:** Middle ear infections can cause subjective tinnitus, but are not typically associated with objective tinnitus.

**Option B:** Otosclerosis is a condition that causes abnormal bone growth in the middle ear, leading to hearing loss, but it is not a cause of objective tinnitus.

**Option C:** Meniere's disease is a disorder of the inner ear that affects balance and hearing, and can cause subjective tinnitus, but is not typically associated with objective tinnitus.

**Clinical Pearl / High-Yield Fact**
Middle ear myoclonus is a rare condition that can cause objective tinnitus, and is often associated with other symptoms such as hearing loss and vertigo.

**Correct Answer: A. Middle ear infections are not a cause of objective tinnitus.**