Anthropogenic noise โ traffic, shipping, aircraft, industrial machinery, wind turbines โ is one of the fastest-growing pollutants on Earth. Unlike chemical pollutants, noise leaves no residue and is invisible to most monitoring; yet its ecological consequences are increasingly well-documented: from disrupted communication and mate choice in birds, to behavioural and physiological stress in marine mammals, to altered community composition in noise-exposed ecosystems.
Noise Pollution โ Ecological Consequences
A 10 dB increase in ambient noise reduces communication area by 90% โ an ecological catastrophe for territorial species.
The Lombard Effect
Animals increase vocal amplitude in noise โ an involuntary reflex documented across birds, marine mammals, frogs, and humans.
Marine Noise Pollution
| Source | Level (dB re 1 ฮผPa) | Impact |
|---|---|---|
| Container ship (1 km) | 150โ160 | Chronic whale-communication masking |
| Seismic airgun (1 km) | 200โ230 | Acute TTS/PTS, mortality |
| Military sonar (MFAS) | 235 (source) | Beaked whale strandings |
| Pile driving | 170โ185 | Fish disorientation |
The masking question
How loud is "too loud"? Auditory masking is well-quantified in psychoacoustics: signals at frequencies near a masker are most strongly affected. Acoustic-niche theory predicts that species in the directly masked band will show the largest behavioural shifts (frequency shift, amplitude increase, timing change), while species outside the masked band may benefit from reduced competition. Field data largely confirm this prediction.