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GATE 2016 CE (CE2) – Question 30

Air Pollution and Municipal Solid Wastes · Air pollution: pollutants, sources, impacts, control and air quality index · 1 mark · Multiple choice

The sound pressure (expressed in µPa) of the faintest sound that a normal healthy individual can hear is

  1. 0.2
  2. 2
  3. 20
  4. 55

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Show answer and explanation

Correct answer: (C) 20

Explanation

The reference pressure used for airborne sound-pressure level is20micropascals, approximately the hearing threshold of a healthy listener near1kHz. Therefore **20µPa, C**. Sound-pressure level uses20log10(p/p0), with this reference pressure as p0.