# Levels of Noise – MCQ || Environmental Engineering ||

## Levels of Noise – MCQ

1. What is the mathematical expression of sound level in decibels?

a) $L = 10. \log_{10} \frac{Q}{Q_{0}}$
b) $L = \log_{10} \frac{Q}{Q_{0}}$
c) $L = \log_{e} \frac{Q}{Q_{0}}$
d) $L = 10. \log_{e} \frac{Q}{Q_{0}}$

a) $L = 10. \log_{10} \frac{Q}{Q_{0}}$.

2. What is the unit of intensity of sound?

a) Pascal.
b) Decimal.
c) Decibels.
d) Bels/meter.

c) Decibels.

3. What is the mathematical expression of sound intensity level in decibels?

a) $L = 10.\log_{e} \left ( \frac{1}{10^{-10}} \right )$
b) $L = \log_{10} \left ( \frac{1}{10^{-10}} \right )$
c) $L = 20.\log_{10} \left ( \frac{1}{10^{-10}} \right )$
d) $L = 10.\log_{10} \left ( \frac{1}{10^{-10}} \right )$

d) $L = 10.\log_{10} \left ( \frac{1}{10^{-10}} \right )$.

4. Which of the following value of reference sound pressure level is considered to measure sound level in decibels?

a) 180μPa
b) 40μPa
c) 20μPa
d) 10μPa

c) 20μPa

5. Which of the following expressions represent the sound pressure level in decibels?

a) $L_{p} = 10.\log_{10} \left ( \frac{p_{rms}}{20 \mu Pa} \right )$
b) $L_{p} = 20.\log_{10} \left ( \frac{p_{rms}}{20 \mu Pa} \right )$
c) $L_{p} = 10.\log_{e} \left ( \frac{p_{rms}}{20 \mu Pa} \right )$
d) $L_{p} = 20.\log_{e} \left ( \frac{p_{rms}}{20 \mu Pa} \right )$

b) $L_{p} = 20.\log_{10} \left ( \frac{p_{rms}}{20 \mu Pa} \right )$

6. What is the maximum sound level that is safe for the human ear?

a) At or below 70 dBA
b) At or below 85 dBA
c) At or above 70 dBA
d) At 85 dBA

a) At or below 70 dBA

7. If you consider 50 decibels noise and want to add another 50 decibels noise, then how much noise it will make up together?

a) 100 Decibels
b) 93 Decibels
c) 53 Decibels
d) 55 Decibels

c) 53 Decibels.

8. What do you mean by the frequency of sound?

a) Number of waves per minute
b) Number of vibrations per unit time
c) Total Number of waves per sec
d) None of these

b) Number of vibrations per unit time.

9. What is the acceptable noise level for hospitals as per BIS code 495-1968?

a) 25 to 30 dBA
b) 35 to 40 dBA
c) 40 to 45 dBA
d) 50 to 60 dBA

b) 35 to 40 dBA.

10. What is the relation between bel and decibel

a) 1 bel equal to 10 decibels
b) 10 bels equal to 1 decibel
c) 1 bel equal to 100 decibels
d) None of these