As a species dolphins have an excellent sense of hearing and rely largely on sound to navigate the ocean, locate food, maintain awareness of threats, keep track of their children and pod members and communicate to one another.
When it comes to communication dolphins communicate using a series high-pitched clicks and whistles, which they produce from their blowhole.
These marine mammals can communicate many different things to one another such as a desire to mate, to alert others when there is nearby danger, to socialize with one another or to let their pod know that they have found food nearby.
Each dolphin can communicate in a slightly different pitch so that other pod members know which dolphin in the group is speaking and to make it easier for pod members to keep track of each others location.
While sound plays a similar role on land it can be even more important for survival in the ocean.
In fact sound travels four times faster in water than it does on land which gives dolphins a big advantage in the ocean compared to other aquatic creatures that do not rely as heavily on sound for their survival.
In addition to using sound for communication dolphins also use sound for echolocation, which allows them to bounce echo’s off of objects in the environment and obtain information from the echo.
By using echolocation and listing to the sound that returns to them dolphins can figure out how far an object is, how fast its moving, how large it is, what direction its moving in, whether its above or below them and whether it is dense or hollow.
While dolphins have an excellent sense of hearing their ability to listen to sounds and echo-locate can be lessened by man-made ambient noises such as sonar (from submarines), loud boat engines, explosives and low flying aircraft; which are all becoming more and more common leaving marine biologists and researchers with concern in regards to the dolphins ability to survive in its environment when surrounded by these man-made noises.
These sounds can make it difficult for dolphins to communicate with one another, accurately locate food and navigate the sometimes pitch-black ocean.
Aside from these possible issues other concerns include the possibility of dolphins beaching themselves due to difficulty navigating the ocean, permanent damage to hearing and hemorrhaging near the dolphins ear and brain tissue, possible decompression sickness from raising to the surface too quickly and difficulty locating food because of ambient interruption during the use of echolocation.
Studies have shown that in areas where large numbers of man-made sounds are present there appears to be a correlation with the higher number of recorded beached whales and dolphins that are found in nearby areas.
There have also been observations made by marine biologists showing what appears to be hemorrhaging of the brain tissue due to these loud sounds.
On the other hand some individuals are speculative in regards to whether or not man created sounds are actually harming these marine mammals.
The reason for this is that some people believe that the number of beaching’s that have occurred over the years has not increased, however with new technology around today (such as cell phones and recording devices) the ability to report these incidents has increased leading to a false perceived increase in the number of beaching’s that are occurring.
In either case researchers and marine biologists are trying to better understand the cause artificial sound has on our ocean dwelling friends.
Man-made sounds that can affect a dolphins sense of hearing
- Sonar
- Boat engines
- Explosives
- Construction
- Loud low flying aircraft