Environmental Science: Numerical Questions – Noise Addition of Noise

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1. A person is exposed to two sound levels of 80 dB and 100 dB simultaneously. What is the average noise level the person experiences?

1. ~97 dB
2. ~87 dB
3. ~90 dB
4. ~93 dB

Explanation:

 Difference (L2-L1) Added to Higher Sound Value 0 3 1 2.5 2 2.1 3 1.5 4 1.5 5 1 6 1 7 0.8 8 0.6 9 0.5 10 0.4
 Difference (L2-L1) Added to Higher Sound Value 0 or 1 3 2 or 3 2 4 to 8 1 9 or more 0

2. On take - off, an aeroplane generates noise level of 120 db. If 5 such aeroplanes take – off simultaneously what will be the noise level?

1. ~126.98 dB
2. ~124.98 dB
3. ~123.86 dB
4. ~122.98 dB

Explanation: L_eq = L_i + 10 Log (n)

L_eq = 120 + 10 Log (5)

L_eq = 120 + 10 ∗ 0.69

L_eq = 120 + 6.9

L_eq = 126.9

3. The resultant of two noise levels of 50 dB and 55 dB is:

1. 58 dB
2. 55.41 dB
3. 52.5 dB
4. 56.19 dB