**Question:** The limit of loudness expressed as decibels that people can tolerate without substantial damage to their hearing is -

A. 85 dB
B. 90 dB
C. 100 dB
D. 110 dB

**Correct Answer:** A. 85 dB

**Core Concept:** Hearing threshold and decibel scale

Hearing threshold refers to the minimum sound pressure level at which a person can perceive a sound. Sound pressure levels are measured in decibels (dB), with higher values indicating louder sounds. The International Hearing Society recommends a daily noise exposure limit of 85 decibels (dB) for an 8-hour period without hearing protection to minimize the risk of permanent hearing loss.

**Why the Correct Answer is Right:** The correct answer, 85 dB, represents the threshold at which humans can tolerate sound without causing substantial hearing damage. This value is based on the International Hearing Society's recommendation for daily noise exposure without hearing protection. However, it is essential to note that prolonged exposure to sounds above 85 dB or loud noises in short periods may still cause temporary hearing loss.

**Why Each Wrong Option is Incorrect:**

B. 90 dB - This is higher than the recommended threshold, which puts individuals at risk for hearing damage even without protection.
C. 100 dB - This represents a significantly louder sound than the recommended threshold, which would cause immediate and severe hearing damage.
D. 110 dB - This is even louder than 100 dB, posing an even greater risk of immediate and severe hearing damage.

**Clinical Pearl:** Understanding the hearing threshold and decibel scale is crucial for recognizing potential hearing risks and taking appropriate precautions when exposed to loud noises. Hearing damage can occur rapidly for sounds above 85 dB, making it essential to be aware of the recommended limit and practice noise-induced hearing loss prevention measures when exposed to noises above this threshold.