Dolphins have the ability to communicate with each other, and for that purpose, they use sounds and body movements. Scientists have been very interested in the way they produce sounds, and the studies they have carried out show that dolphins are animals with a diversity of sounds and a complex language.

Sound waves travel nearly 4.5 times faster in the aquatic environment than in the air. The sounds are essential in the life of any dolphin and in general, of any cetacean. Dolphins communicate, hunt, avoid predators and orient themselves when navigating through sound emissions in the water, therefore, they are very sensitive animals to noises emitted in and out of the water.

Not all sounds are the same. They vary in frequency, volume, wavelength and pattern and depend on the intention or the situation in which the dolphins are. If they are scared, excited or in a context of socialization, they tend to make whistles, but if they are in trouble, they make clicks with their jaws. In general, they communicate using low-frequency sounds but emit other high-frequency signals when using echolocation.

Most people have heard the chirping, squeaking noises made by dolphins which they use to communicate with other dolphins or for echolocation. Dolphins can use echolocation to detect even a three-inch object as far as the length of a football field.

Sounds are essential in the life of any dolphin and in general, of any cetacean.

TYPES OF SOUNDS

Within the range of sounds that dolphins produce are whistles, squeaks, crunches, clicks and some similar to screams. From a general perspective, the sounds can be burst-pulsed or frequency modulated. Sometimes a separation of a burst of clicks to the previous ones is made when used for echolocation and not precisely for communication between the members of a pod.

Dolphins produce frequency modulated sounds by changing the tone while emitting them, that is, it can go up or down. Pure whistles, squeaks, and squeals are frequency modulated sound. Bottlenose dolphins have a “signature whistle,” well differentiated from other sounds, which identifies a particular dolphin from the others.

On the contrary, the burst-pulsed sounds are brief, emitted successively and at regular intervals. In this category are clicks and bursts produced when the cetacean emits clicks remarkably fast.

DOLPHIN COMMUNICATION PROCESS

Dolphins produce sounds from the vibrations of an air sac in their respiratory cavities. They lack vocal cords, so they are unable to make emissions with them.

Production and emission.
When the air enters through the blowhole the nasal air sacs swell and Some structures of the nasal passages, called phonic lips, open and close continuously, making vibrate the surrounding tissues, generating sound waves.

The waves group in bundles in the melon and the dolphin directs them forward. Then the sound waves bounce back when they find objects in their path.

Reception.
Part of the signal bounces back and returns to the dolphin as an echo. It may seem strange, but the bones of the lower jaw are the principal areas of reception of sounds. From there they travel to the inner ear and then to the auditory centers of the brain.

Interpretation.
The brain receives the returned sound waves in the form of nerve impulses, and the dolphin can interpret the echo.

One of the primary uses of sounds by dolphins is for echolocation, which is an ability of Odontoceti cetaceans, based on the emission of sounds and the interpretation of their echo.

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 a language.

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 lexicon of danger sounds, food sounds, seeking sounds, and sometimes they put these sounds together in a reasonably sophisticated fashion. There is evidence that they may greet one another by name because they utter unique sounds when meeting other dolphins.

DOLPHINS AND MAN-MADE SONAR

Dolphins are incredibly good at distinguishing their echolocation sounds even in very noisy underwater environments. It has also been found, though, that some noisy locations confuse dolphins.

Beaching is probably the most tragic thing that we 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 accepted theory is that something confuses their echolocation, taking them to the beach instead of the open ocean. Some autopsies of beached dolphin bodies show a very high percentage of damaged hearing, suggesting that a powerful sound may have blown out their hearing.

Although dolphins see quite well, without their hearing sense, they are disoriented and blinded. And when one dolphin beaches itself, the others are at risk because they will try to help it.

References

https://dolphins.org/acoustics

http://biol.wwu.edu/mbel/media/pdfs/AquatMamm2004_30.pdf

https://www.uaeh.edu.mx/scige/boletin/prepa3/n1/r2.html

Janik, Vincent; Laela Sayigh (7 May 2013). “Communication in bottlenose dolphins: 50 years of signature whistle research”. Journal of Comparative Physiology.

Dolphin Mysteries: Unlocking the Secrets of Communication. Yale University Press. 2008.

Denise L. Herzing. Dolphin Communication and Cognition: Past, Present, and Future. MIT Press, 2015.

Echolocation is a process that permits dolphins to send out sound waves that when they hit an object, are bounced back, allowing them to identify the location, shape, and size of such object.

The amount of time it takes for the sound waves to come back help them to determine the distance, as it takes longer the sound waves to return when there is more distance between the dolphin and that given object.

The first person to look at echolocation thoroughly and to document the findings was Jacque-Yves Cousteau. He wrote about it in a book published in 1953 called The Silent World.

Echolocation or biosonar is the ability of some animals to locate objects through sound waves, that is, sounds. Many animals, including odontocete cetaceans and some bats, make use of echolocation to orient themselves and detect prey.

The process of evolution of dolphins gave them this ability that allowed them to survive in the aquatic environment. In water, the sound waves travel 4.5 times faster than in the air, so echolocation is the perfect resource that facilitates their survival.

WHY DOLPHINS USE ECHOLOCATION?

Dolphins need echolocation to navigate, locate prey, hunt, protect themselves from predators in murky waters or where there is no sunlight and to communicate. In fact, in deep dark waters, their sense of sight is almost nil, but they do not need it because they can detect and chase fast prey through the emission of sounds.

Most odontocete cetaceans can emit very high-frequency sounds. In this sense, the frequencies vary according to the species, but there are general characteristics in all dolphins. For example, they always communicate with low-frequency signals, which include whistling or chirping; But they emit high frequencies when using echolocation. The sounds vary according to the circumstances and the purpose.

Dolphins need echolocation to navigate, locate prey, hunt, and protect themselves.

HOW DO ECHOLOCATION WORKS?

First, is necessary to know that dolphins are devoid of vocal cords, so they do not have a “voice” like that of humans. Instead, they generate sounds through other internal structures.

Step number 1: Generate sounds.

Dolphins produce sounds from the nasal air sacs, the blowhole, the larynx, the lungs, and the melon; This latter is an organ located in the upper inner area of ​​the head filled with low-density lipids.

First, the dolphin opens the blowhole to make an inhalation and the nasal air sacs swell as the air enters the lungs. Then the dolphin exhales: the air resonates in the nasal sacs and comes out with pressure through the blowhole. Vibrations occur in the larynx, and the nasal air sacs deflate.

For echolocation, dolphins emit ultrasounds called “clicks” by pushing air between the phonic lips of the nasal passages. When these lips open and close, the surrounding tissues vibrate and produce sound waves.

The passage of air through the respiratory cavities generates the sounds.

Step number 2: Amplify sounds.

The Dolphins have an organ in the head, called melon, that allows the transmission of the sound waves.

The melon concentrates the pulsations that the dolphin emits and sends them forward. The primary “function” of this organ is to group sounds into beams and produce and amplify the resonance.

Once the emission is released forward, the sound waves bounce back in the objects that are in the water.

Step number 3: Reception and interpretation of sounds.

A part of the signal bounces back in the objects and returns as an echo to the dolphin. Their brain receives the sound waves in the form of nerve impulses, and the dolphin can interpret this echo.

The receiver of the returning sound waves is in the lower jaw, and the teeth of dolphins work like antennas to receive the signals. It is a very complex adaptation vital for their survival.

The intensity, pitch, and time that it takes the echo to return to the dolphin provide information about the target, such as its size, shape, composition, position, distance, and direction. Based on this, the dolphin builds an image of its environment and the object.

Echolocation has been studied in bottlenose dolphins (Tursiops truncatus), although there are still underlying aspects that are not entirely understood. For now, scientists see echolocation as a learning opportunity to create new communication technologies in some areas of human life.

DOLPHIN ECHOLOCATION

What is known is that dolphins have the ability through echolocation to emit sounds with a frequency of 120 kHz and humans, with excellent hearing, can hear sounds with frequencies ranging from 20 Hz to 20 kHz. Even dogs and cats that have amazing hearing capabilities do not compare to dolphins. Dogs hear up to 45 kHz, and cats up to 65 kHz.

However, high-frequency sounds don’t travel very far in the water while Low-frequency sounds have more energy and can reach greater distances. Most of the time, dolphins will get the best results with echolocation when the object is from 16 to 656 feet from them.

Excessive noise in the environment should be upsetting for dolphins and can cause them to lose their hearing over time. It can also disorient them and disrupt their navigation systems.

References

Kathleen Dudzinski, Toni Frohoff. Dolphin Mysteries: Unlocking the Secrets of Communication. Yale University Press, 2014.

Jeanette A. Thomas, Cynthia F. Moss, Marianne Vater. Echolocation in Bats and Dolphins. University of Chicago Press, 2004

Whitlow W.L. Au. The Sonar of Dolphins. Springer Science & Business Media, 2012.

https://link.springer.com/chapter/10.1007/978-1-4612-1150-1_9#page-1

https://seaworld.org/en/animal-info/animal-infobooks/bottlenose-dolphins/communication-and-echolocation

Every living thing has a method of communication, and it is fascinating to explore the depths of it. For example, humans use short words the most. Some of the most commonly used words are I, a, and the. This is a means of being efficient in communication, and dolphins are believed to follow similar types of patterns in their communication efforts as well.

This is referred to as the Law of Brevity, and it has become a very interesting and valuable area of study. It has been able to show that evolution plays a key role in communication in both humans and animals. Such studies also show animals are more capable of effective communication than humans once gave them credit for.

One person that has been involved in such studies is David Lusseau, a Behavioral Ecologist at the University of Aberdeen in Scotland. He believes that the Law of Brevity tells us a great deal about ourselves. It also explains many of the levels of complexity in the world regarding communication. There are still unknown factors though such as if it is limited or if there are so many ways to reach it that it is limitless.

The desire of Lusseau to learn more about the complexities of communication systems led him and to study dolphins along with a colleague, Ramon Ferrer-i-Cancho. They chose to study dolphins due to the fact that they are distanced from humans on the tree of evolution. Approximately 65 million years ago they split from humans, and they have brains that are designed different from those of humans.

Studies show that dolphins have the ability to use about 30 different nonverbal behaviors that allow them to effective communicate. However, we don’t have all the information to really understand the messages being sent all the time. For example, a dolphin that does a side flip or several of them is sending a message to the rest of the group. Are they telling them to follow the hierarchy within the group or is there another message from this movement?

To get the most out of the research efforts, all of the 30 behaviors were broken down individually into behavioral units. A flip equals 2 units while a head butt equals 4 units. There were hundreds of hours invested in observing and analyzing the dolphins. This included very simple behaviors as well as those that are quite complex.

The Law of Brevity is exhibited in all human languages, and it is evident in these observations of the dolphins too. Basically, when you have more to say, finding a shorter way to communicate it will save you time and deliver the message faster. At the same time, the listener is able to use less effort to understand that message being said to them. This all improves communicate results.

This type of study with the dolphins is just the tip of the iceberg. Many scientists including Brenda McCowan of the University of California have the theory that there are plenty of other types of animals that use the Law of Brevity as well. She believes that there are various systems in place when it comes to communicate that are structured in a manner that works for that type of animal.

As more data is compiled and analyzed, it shows that humans aren’t unique when it comes to communication and the Law of Brevity. McCowan encourages us to be open to the idea and to think about how it affects our relationships with animals in the world. It can help us to see how animals fit into society differently than we imagined before.

Source: http://dsc.discovery.com/news/2009/08/11/dolphin-language.html

Dolphins can make a large range of different sounds using a unique part of their anatomy called nasal air sacs.

Such air sacs are located just behind their blowhole.

They produce three different varieties of sounds.

Whistles.
Modulated in frequency and usually used for communication.

Burst-pulsed sounds.
Also used for communication.

Clicks.
Used for echolocation. A burst of clicks is called a click train.

There is always an ongoing debate about dolphin intelligence. While most scientists agree about the problem-solving capabilities of dolphins and their advanced communication skill, they still argue about how smart are dolphins.

It is a fact that they can use tools to solve problems, very much like apes. They are also excellent communicating and learning new ways to interact as many investigations are about human-dolphin and dolphin-dolphin communication.

Dolphins can do intelligence tests, and they perform brilliantly on them, so they are problem solvers.

Even more, there is evidence that in some species they can transmit knowledge to new generations, very much like we do.

Read more about Dolphin Intelligence

Dolphins communicate through a group of several specialized sounds and whistles. There are several kinds of them used by these cetaceans.

Some species of dolphins can send identity information through signature whistles.

Whistles also coordinate group hunting which makes feeding much easier and efficient for dolphins than doing it alone.

Burst-pulsed sounds are also made by dolphins with the purpose of communication, although there is not enough knowledge about dolphin communication.