Air Pollution: Causes, Effects and Control · NCERT Biology

A sound level of ________ is considered the threshold for 'noise' that can cause pain or discomfort.

  1. 40–50 dB, typical of a quiet library
  2. 60–70 dB, the level of normal speech
  3. 80–90 dB, loud city traffic noise
  4. 120–130 dB, at which physical pain occurs
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Correct answer: 120–130 dB, at which physical pain occurs

While constant exposure to 80 dB can cause hearing damage over time, sounds reaching 120–130 dB (like a loud siren or rock concert) reach the threshold of pain for the human ear. Immediate physical discomfort occurs at these levels.

Difficulty: Medium Question 18 of 20

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