A magnificent blue whale
Pollution can take numerous and unexpected shapes; one of the not-so-deadly, but still extremely unpleasant types is noise pollution. You probably don’t notice it because it’s so common, but it’s a really noisy world out there; if for a few days you were to go somewhere far away from all the fuss and noise that affect us on a daily basis, you will probably have a hard day when you come back, before you get used to all the sounds again.
The world's shipping routes. Credit: National Center for Ecological Analysis and Synthesis.
It is true that all environments have some kind of ambiental noise, caused by rivers, waves, other animals, wind, etc, but we humans have drastically increased the amounts of daily decibels out there. Basically, on land we’re dealing with cars, airports, machinery, and in the sea the problem is mostly caused by shipping, but also deep water drilling, explosions, etc. This may not seem like a big issue, but when some of the most important things in your life, like hunting and mating, are determined by sounds, you definitely have a problem on your hands.
Animals have always had ways to deal with the sounds; when it comes to short term ones, such as wind or rain; most just wait until it stops and then continue their activity. Tawny owls, for example, stop calling each other, and bushcrickets delay their nocturnal symphonies until morning when there are other noisy insects around. But anthropic noises are not short term, and humans have always been remarkably good at making noise.
Tawny Owl
The next usual approach animals take is being even louder than before. It’s something natural, everybody does it all the time (even though it’s not really a good idea, for example when your mother or daughter is screaming at you). But this comes at a cost; have you ever been to a really good concert ? If you have, the odds are you’ve come home with a really sore throat caused by screaming. This phenomenon was first described by Etienne Lombard 100 years ago, and since then, it has been used to describe the increase in amplitude of a vocalization.
Research upon Great tits, Beluga whales, orcas, manatees and numerous other species has shown that this effect can be quite common – especially as it requires quite some effort to scream all the time. This may be what causes blue whales to sing lower and lower every year, but there still is a lot we have yet to understand about the changes species undergo from loud noises.
However, one thing is loud and clear – the sounds we make have a definite impact on animals, and many of them are out there right now, screaming “Can you hear me?” louder and louder every day. Surprisingly, the answer is no.
