Studies have shown that people exposed to constant noise are more stressed out. I’m not sure whether that’s true of animals (although I’m not sure why it wouldn’t be), but it does seem that even small amounts of noise might affect how animals interact.

the acoustic ecology institute

NPS study: moderate noise can have major impacts on animals

December 13, 2009

An ongoing research project from the National Park Service Natural Sounds Program is about to publish a groundbreaking paper that outlines the many ways that even moderate increases in human background noise can create major impacts on animals.  The study proposes a new metric for use in bioacoustics research, the “effective listening area.”  This is the area over which animals can communicate with each other, or hear other animals’ calls or movements; as might be expected, animals focus especially on listening for sounds at the very edges of audibility, so that even a small increase in background noise (from a road, wind farm, or regular passing of airplanes) can drown out sounds that need to be heard.  The authors note analyses of transportation noise impacts often assert that a 3dB increase in noise – a barely perceptual change – has “negligible” effects, whereas in fact this increased noise reduces the listening area of animals by 30%. A 10dB increase in background noise (likely within a few hundred meters of a road or wind farm, or as a private plane passes nearby) reduces listening area by 90%.

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