## Core Concept
The stapedial reflex, also known as the acoustic reflex, is a protective mechanism of the middle ear that involves the contraction of the stapedius muscle in response to loud sounds. This reflex helps to reduce the intensity of sound reaching the inner ear, thereby protecting it from potential damage.

## Why the Correct Answer is Right
The stapedial reflex is typically elicited at sound intensities around 70-90 dB SPL (sound pressure level) in individuals with normal hearing. This reflex threshold is an important indicator of middle ear function and can be used in the assessment of hearing and middle ear disorders.

## Why Each Wrong Option is Incorrect
* **Option A:** This option is incorrect because the stapedial reflex threshold is generally not as low as 30-50 dB SPL; such low sound levels are typically within the range of normal conversation and would not trigger the reflex.
* **Option B:** This option is incorrect because, although 50-70 dB SPL is still on the lower side, some individuals might exhibit the reflex starting at around this range, but it's generally considered that the reflex is more consistently elicited above this range.
* **Option D:** This option suggests a much higher threshold (110-130 dB SPL) than what is typically required to elicit the stapedial reflex; such high sound levels are hazardous and far exceed the threshold for eliciting the reflex in a normal-hearing individual.

## Clinical Pearl / High-Yield Fact
A key clinical point to remember is that the absence of the stapedial reflex or an elevated reflex threshold can indicate a problem with the middle ear system, such as otosclerosis, or with the nerve pathways controlling the reflex. This reflex is an important tool in audiologic assessments.

## Correct Answer: C. 70-90 dB SPL