Voice induced impairment of hearing at –
**Core Concept**
The question is testing the concept of noise-induced hearing loss (NIHL), a condition where prolonged exposure to loud sounds damages the hair cells in the inner ear, leading to permanent hearing impairment. This is a common occupational hazard and a significant public health concern.
**Why the Correct Answer is Right**
The correct answer is related to the concept of the "noise dose" or the cumulative effect of prolonged exposure to loud sounds. The threshold for noise-induced hearing loss is typically considered to be above 85 decibels (dB) over an eight-hour period. Prolonged exposure to sounds above this threshold can cause permanent damage to the hair cells in the inner ear. This is because the hair cells in the cochlea are sensitive to mechanical stress, and repeated exposure to loud sounds can cause them to become damaged or die.
**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because the threshold for noise-induced hearing loss is typically considered to be above 85 dB over an eight-hour period.
**Option B:** This option is incorrect because the threshold for noise-induced hearing loss is not typically considered to be above 100 dB over a short period of time.
**Option C:** This option is incorrect because the threshold for noise-induced hearing loss is not typically considered to be above 120 dB over an eight-hour period.
**Clinical Pearl / High-Yield Fact**
It's worth noting that the effects of noise-induced hearing loss can be cumulative, and repeated exposure to loud sounds can cause permanent damage to the hair cells in the inner ear. This is why it's essential to take regular breaks when working in noisy environments and to wear ear protection when exposed to loud sounds.
**Correct Answer:** C.