Dolphins are one of the most social mammals. They are highly intelligent as well, utilizing their communication skills to both cooperatively hunt and learn what is socially acceptable within a pod. Their advanced sounds allow dolphins to understand what is in front of them, even when the water they are in is dark or murky, and alert others to danger when it exists.
But just how many sounds does a dolphin make to communicate all of this information? Scientists have been trying to decipher the sounds dolphins make for decades. This has proven to be challenging, as different pods within the same species exhibit dialects that differ from one another. Therefore, there are generalities when it comes to the number of sounds dolphins can make. But the sounds have been categorized so that there is at least a broad understanding of what each sound means.
Dolphins Have The Ability To Make Different Sounds
There is no true count of just how many different sounds each species of dolphin can make.
©Elena Larina/Shutterstock.com
Depending on the source, there are varied answers regarding the number of distinct sounds dolphins can produce. Some state the number is as high as 1,000 different sounds. Others have the figure significantly lower. When examining the bottlenose dolphin, the most studied of all dolphins, the species is capable of producing 40 distinct sounds. This has been noted in their whistles and clicks, primarily. Not all clicks can be heard, however, and these dolphins have been recorded clicking “1,750 times per second.” This frequency is not something people can hear and is used for echolocation.
Interestingly, some species of dolphins do not whistle at all. Those species, according to the Dolphin Communication Project, include the harbor porpoise, Hector’s dolphin, and Commerson’s dolphins. It is unclear whether this means they have a smaller sound vocabulary than bottlenose dolphins, but the sounds are certainly more limited. Therefore, it is species-specific as far as how many sounds a dolphin makes. Those that make multiple sounds have had some of them interpreted over the years, showing just how diverse the communication between dolphins truly is.
What Do the Different Sounds That Dolphins Make Mean?
Dolphins have five distinct sounds that have different meanings attached to them.
©Curioso.Photography/Shutterstock.com
The sounds that dolphins make are not done without reason. Each of the sounds they make serves a purpose, whether to warn others in the pod or simply for entertainment. This is why dolphins’ sound vocabulary is so large. The meanings behind dolphins’ sounds include:
| Sounds That Dolphins Make | Meaning Behind The Sound Dolphins Make |
| Whistle | Each whistle is unique to a dolphin. No two are the same. Dolphins use whistles to identify themselves and for communication with dolphins they are close to, such as with a mother and calf. |
| Click | Clicks are generally used for echolocation. However, clicks are also used to identify if another dolphin is a part of the pod or not, even in conditions where the dolphin cannot be seen. |
| Burst-Pulse Sounds | Burst-pulse sounds are used when dolphins are happy or excited. The dolphins will use these sounds to communicate with others in their pod for playful interaction as well. |
| Squeals or Screams | Squeals or screams are used in a time of distress. This could be when being chased by a predator or if injured. The sounds can also be used as a warning to others in the pod. |
| Codas | Codas are repetitive sounds that dolphins make. These sounds are used when trying to coordinate an activity as a group. |
Because dolphins tend to use noise to communicate, there is less visual communication that occurs. However, with the visual communication used, it can put the sounds being emitted into context. This has helped scientists better understand what dolphins are saying or the emotion behind their sounds, both in captivity and in the wild.
Some of the most common visual communication cues used by dolphins include:
- Arching the head and tail
- Rolling eyes to show the whites of the eyes
- Shaking the head from side to side
- Lying on the side as a sign of submission
- Sudden head jerk, generally accompanied by a sound
On their own, these movements do not mean much. But with the sounds made, people have been better able to understand what dolphins are trying to communicate.
How Dolphins Make Noise Underwater
Dolphins use air trapped in nasal sacs to produce sound underwater.
©Tetsuo Arada/Shutterstock.com
When dolphins are out of the water, they produce sound via their blowhole. Dolphins also create sounds when they are underwater. But when this is done, the blowholes are closed. Therefore, the sound comes from another location. Just how these sounds are made is still being understood by scientists. However, there are two hypotheses that the scientific community believes are most plausible.
The most widely accepted hypothesis regarding how dolphins produce underwater noise is that they utilize their nasal sacs for communication. As dolphins dive, they fill three air sacs beneath the blowhole. Each air sac has a nasal plug. As air from the air sac is pushed past the nasal plug, sounds of all types are emitted from dolphins. Another theory is that the air sacs “act as an acoustical mirror” to the sound that is being passed through the fatty tissue beneath the blowhole. The fatty tissue is in layers that “act like lips” as the sound moves through them.
How Dolphins Hear Sounds
Dolphins do not have external ears, but they have small openings on the sides of their heads that allow them to hear above the water. They use their jawbones to transmit information to their inner ears when underwater.
©Andrea Izzotti/Shutterstock.com
Looking at a dolphin, there are no external ears for them to receive the sounds being sent their way. Does that mean they do not have ears and hear the noises of their fellow dolphins in another way? Dolphins do have ears, but their hearing mechanism is quite different from that of humans.
Dolphins have small ear openings on the side of their heads to hear. But their ears are only used when they are not underwater. When underwater, dolphins receive messages from one another via their lower jawbone. This bone then transmits the messages to the receptive portions of dolphins’ middle ears. Dolphins’ sense of hearing is seven times more sensitive than that of humans. Where adults can hear from 20 Hz to 20 kHz, dolphins can hear from 20 kHz to 150 kHz. The range may be slightly higher for children, as they have not been exposed to loud noises that can eventually wear down the frequencies that can be heard.
These same sound waves are used with echolocation. By sending out sound waves into the water, dolphins receive a message back when the frequencies hit an object. The use of echolocation enables dolphins to detect objects in the water without needing to see them. This is why dolphins continue to be studied and trained decades after the Navy wanted to develop echolocation. As much as the military wants to develop echolocation as sophisticated as that of dolphins, it has never been able to match the way dolphins can determine precisely what is in the water by sound alone.
The way dolphins create and use sound is incredible. It is truly amazing how they can communicate with each other over both short and long distances to signal a need for community, warn of danger, and the like. People may not be able to understand what all the sounds make at the moment. But technology is advancing to the point where someday, even the clicks and whistles that are not currently understood may just be unlocked, and along with it, a greater understanding of the intelligence dolphins possess.
