GATE 2022 AR — Architecture – Question 64
A panel has absorption coefficients at 63, 125, 250, 500, 1000, 2000, 4000, 8000, 16000 Hz of 0.1, 0.2, 0.5, 0.5, 0.7, 0.8, 0.8, 0.9, 0.9 respectively. Find its Noise Reduction Coefficient, rounded to two decimals.
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Correct answer: 0.60 to 0.65
Explanation
NRC averages the 250, 500, 1000 and 2000 Hz absorption coefficients, not all nine bands. Their mean is(0.5+0.5+0.7+0.8)/4=0.625. Report 0.63 to two decimal places. If expressing the conventional nearest 0.05 NRC rating, the value is 0.65; both fall within the official accepted interval.