Question

Ambient noise level in resident area is
A. 75/70 dB
B. 65/55 dB
C. 55/45 dB
D. 50/45 dB

Answer 1

Hint: Ambient sound is the level of sound which is relatable to human hearing. It is measured in decibel (dB). Continued exposure of noise above the ambient level causes hearing loss.

Complete Answer:
- Sound is a phenomenon caused by vibrations which is sensed by our ears. The unwanted sound is called noise. Sound becomes noise when it disturbs sleep or conversation.
- Ambient noise levels are measured to provide a reference point for analyzing an intrusive sound to a given environment.
- Aircraft noise is studied by measuring ambient sound without presence of any overflight. The noise addition is measured by computer simulation of overflight events.
- Resident area is the area in an urban or rural town. If the noise level exceeds the ambient level then it can cause several side effects like headache, hearing loss. The committee of noise pollution control has set up a permissible limit for day and night.

(I) For the day time the ambient level is 55db and that of night is 45dB. The peak noise is considered to be 70dB.
(II) For commercial areas- Ambient noise is considered to be 65/55 dB.
(III) For industrial areas, the ambient noise is 75/70dB.
(IV) For silent zones, the ambient limit is 50/45dB.

The correct answer is C. Ambient hearing in residential areas is 55/45dB.

Note: Ambient noise level is measured with a sound level meter. It is measured in decibel relative to the reference pressure of 20 micropascal. Most ambient noise is measured using a relative frequency. Continued exposure of noise above 85dB can cause permanent hearing loss.