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Relevance: GS-III (Environment & Ecology) | Source: The Hindu
The Context: We usually link pollution with plastic or dirty air, but a major global study in Science warns that human-made noise (anthrophony) is an invisible crisis. From highway traffic to ship sonar, constant noise is damaging the health, hunting habits, and survival of wildlife worldwide.
1. Key Findings: The Scale of the Noise Crisis
- Wide Impact: Reviewing over 200 studies across six continents, scientists found that human noise harms the body or behaviour of 80% of studied animal species.
- Higher Death Rates: Long-term noise stress causes a 138% jump in death rates across many species and lowers their overall survival fitness by 27%.
- Predator-Prey Trap: Noise drowns out natural sounds (acoustic masking). Predators had to work 150% harder to hunt yet caught 25% less food, while panicked prey animals ran out of safe hiding spots right into danger.
2. Core Concepts: Ocean Noise & Body Stress
- Why Oceans Suffer More: Because water is denser than air, sound travels 4.5 times faster in water (~1,500 m/s vs. 343 m/s in air) and goes much farther. Loud cargo ships, oil drilling, and naval sonar blind whales and dolphins that use sound (echolocation) to navigate and find food.
- Internal Damage: Constant noise spikes stress hormones (like cortisol), weakens immunity, damages cells, and ruins mating calls in birds, frogs, and insects.
Practice MCQ
Q. Consider the following statements regarding noise pollution and its ecological impacts:
- Sound waves travel faster and farther through water than through air, making marine species highly vulnerable to underwater noise pollution.
- India’s Noise Pollution (Regulation and Control) Rules, 2000 prescribe dedicated decibel limits specifically for Eco-Sensitive Zones and wildlife corridors.
Which of the statements given above is/are correct?
(a) 1 only (b) 2 only (c) Both 1 and 2 (d) Neither 1 nor 2
Answer: (a) 1 only
Hint: Statement 1 is correct; sound travels ~4.5 times faster in water than air, severely affecting marine animals that rely on echolocation. Statement 2 is incorrect because the Noise Pollution Rules, 2000 (under the EPA, 1986) only set day/night decibel limits for four human zones (Industrial, Commercial, Residential, and Silence zones around hospitals/schools/courts), not dedicated wildlife corridors.
Hint: Statement 1 is correct; sound travels ~4.5 times faster in water than air, severely affecting marine animals that rely on echolocation. Statement 2 is incorrect because the Noise Pollution Rules, 2000 (under the EPA, 1986) only set day/night decibel limits for four human zones (Industrial, Commercial, Residential, and Silence zones around hospitals/schools/courts), not dedicated wildlife corridors.
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