With reference to Noise pollution, consider the following statements:
1. An increase of about 10 dB is approximately double the increase in loudness.
2. The World Health Organisation recommends that sound levels indoors should be less than 40 dB.
3. The noise pollution-reducing techniques include control over vibration, designing of buildings and green belt development (planting of trees).
Which of the statements given above are correct?
(a) 1 and 2 only
(b) 2 and 3 only
(c) 1 and 3 only
(d) 1, 2 and 3
Explanation Statement 1 is correct: An increase of about 10 dB is approximately double the increase in loudness. In the decibel (dB) scale, the loudness of sound increases logarithmically, not linearly. According to the sound intensity rule, every 10 dB increase means the sound loudness doubles.
For example: 50 dB → normal conversation; 60 dB → twice as loud as 50 dB; and 70 dB → four times as loud as 50 dB.
Statement 2 is not correct: According to the World Health Organisation (WHO), the recommended indoor sound levels are:
● Good sleep: Should be less than 30 dB.
● Effective learning in classrooms: Should not exceed 35 dB.
Excessive indoor noise can lead to sleep disturbances, stress, and decreased cognitive performance.
Statement 3 is correct: Techniques to reduce noise pollution include:
● Control over vibration: Reducing vibrations from heavy machinery, traffic, or construction helps minimise noise pollution.
● Designing of buildings: Soundproof buildings with insulated walls, double-glazed windows, and proper orientation reduce noise infiltration.
● Green belt development (planting of trees): Dense tree plantations act as a natural sound barrier, reducing ambient noise levels.
Kutos:Environment & Ecology Expert
Hello! I am a Environment & Ecology expert. You can ask any question or request a detailed analysis related to this topic.
