Dolphin Sounds and Acoustics

Dolphin Sound Diversity

Most people have heard the chirping, squeaking noises made by dolphins which they use to communicate with dolphins and human trainers, and to navigate by using echolocation, or figuring out where things are by bouncing sound off them. Did you know dolphins can use their echolocation to detect three-inch objects further away than the length of a football field? Or that the possibility of true language exists, according to the theories of some researchers?

Do Dolphins Have Language?

Whether or not dolphins have language is a matter for debate unless and until we humans figure out how to speak to them. But evidence is mounting that dolphins may indeed have their own language.

Pods of dolphins in the English Channel stay on their own side – the French-water dolphins on the France side and the English-water dolphins on the England side – even though they are of exactly the same species and might be expected to mingle more. Some researchers say that this indicates not just language, but that two groups have developed distinct language that can’t be understood by the others.

Whether you buy that or not, there is a lot of research on dolphin vocabulary that indicates they communicate with at least as much sophistication as the higher apes. They have a vocabulary of danger sounds, food sounds, and seeking sounds, and sometimes put these sounds together in a reasonably complex fashion. There is also evidence that they may greet one another by name; specific sounds are only uttered when meeting certain dolphins. Dolphins and Man-Made Sonar

Because of millions of years of evolution, dolphin echolocation abilities are much superior to those of any man-made device. For this reason, the US Navy have been studying them for years in order to improve their own sonar. What they’ve found has been surprising.

Dolphins are incredibly good at distinguishing their own echolocation sonar even in very noisy underwater environments – and in fact are very good at locating the drift nets that entangle and kill so many of them, raising the question of why they are still often trapped in them. It has also been found, though, that some noisy locations confuse dolphins, perhaps explaining why dolphins often ground themselves in areas where Navy ships using active sonar are performing maneuvers. Could the clumsier man-made sonar be using frequencies the dolphins associate with something else? Or perhaps it’s like looking into a strobe light for them. Whatever the explanation, the Navy is interested in eradicating the problem.

Dolphin Beaching

It’s the most tragic thing a dolphin lover can see: a pod of dolphins that have apparently killed themselves by swimming onto a beach and lodging themselves there. Why do dolphins do this?

The most prominent theory currently is that something confuses their echolocation, “blinding” them to the location of the beach in relation to the open ocean. Since many beachings happen near man-made sonar activity, it’s possible that this impacts them. Some very recent autopsies of beached dolphin bodies show a very high percentage of damaged hearing, suggesting that a very powerful sound somewhere may have basically blown out their hearing. Dolphins see quite well, but without their ears they are disoriented and blinded. And when one dolphin beaches itself, the others are at risk because they will try to help him

However a beaching is initiated, it’s likely that it has much to do with how a dolphin perceives sound. Hopefully, we’ll soon understand enough about dolphin hearing to be able to prevent these tragedies.