American Oceans

What Is Sonar?

Sonar, which is short for “Sound Navigation and Ranging” is used to help both explore and map the ocean.

It is especially useful in ocean exploration because sound waves have the ability to travel more efficiently through the water (and farther) as opposed to light or radar waves, which have also been used in the past to help explore the ocean.


More specifically, NOAA scientists mainly use sonar as a way to locate different objects on the ocean floor (such as shipwrecks) as well as locating any underwater hazards to help create more complex and advanced maps.

In addition to this, sonar is also used to develop nautical charts.

At the time of writing, the two types of sonar that are used by scientists are active sonar and passive sonar. Let’s take a closer look at both of them below:

Active Sonar:

The first type of sonar is active sonar.

reflected wave sonar

When used in the ocean, active sonar transducers are able to emit an acoustic, pulsing sound in a wave-like fashion throughout the water, and if an object is found across the path in which the sound wave is traveling, the sound will then bounce off of the object and send an echo straight back to the sonar transducer.

Then, if the transducer has been equipped with the ability to receive echo signals created by the sound wave, it will then be able to measure how strong the signal is.

After accurately measuring and determining the duration of time between the emission of the echo and the sound wave’s reception, it will then mean that the transducer is able to then determine the exact location of the object so that scientists can then explore what it is, and whether or not might be a hazard.

Passive Sonar:

Passive sonar is the second type of sonar used by scientists. Unlike active sonar, passive sonar systems are used by NOAA scientists as a way to detect noise from marine objects, including both submarines and ships.

In addition to that, passive sonar is also used to detect the sounds of other underwater activity, including marine animals including whales.

sonar screen

Additionally, unlike active sonar, passive sonar is not able to emit its own signal back to the transducer, which is both a good and bad thing.

On one end of the spectrum, it makes it harder for scientists to locate the exact location of underwater objects, which can be an issue when trying to create maps or locate an object.

On the other hand, however, passive sonar can be an advantage for military submarines that do not want to be located by scientists.

Additionally, it is also worth noting that passive sonar is unable to properly measure the exact range of an underwater object unless it has been used in combination with other devices that are able to measure the location.

How does sonar affect marine life?

If you’ve ever attended a concert or went to watch a sport being played in a stadium, then we’re sure that you’ll be familiar with the feeling of “ringing” in your ears, that lasts for a few hours after you have left the venue.

This type of ringing in the ears is very similar to the type of experience that underwater marine creatures experience when they are exposed to sonar sound waves, and that goes for both active and passive sonar, too.

The only difference? For marine life, the feeling of ringing in the ears is much, much more intense.

According to many different studies that have been undertaken, it is estimated that the underwater sounds produced by both active and passive sonar are so powerful as they travel through the water, that they are able to emit sound waves.

As this powerful wave is spread throughout the ocean, it can be severely uncomfortable and even painful to the marine that comes into contact with it or crosses its path.

For this reason, sonar has been met by much criticism by environmentalists and animal welfare groups, alike, and some groups have even successfully been able to introduce stricter control of sonar, particularly that of military activity.

Can sonar affect whales?

Yes, sonar can affect whales, although more research needs to be done to determine to what extent sonar affects whales, whether sonar affects all types of whales, as well as whether both active and passive sonar affects whales, too.

As of right now, there has been research conducted which suggests that both beaked and blue whales are especially sensitive to mid-frequency active sonar, as it has been noted that these two whale species move away rapidly from the sound waves when they come into contact with it.

Besides affecting whales, sonar can have a catastrophic effect on whales, causing them to become stranded and even unable to properly feed in certain areas.

Do all whales use sonar?

Whales do not use sonar to communicate with other whales and hunt for prey, instead, they use something which is quite similar and known as echolocation. In a nutshell, echolocation is a type of sound frequency that is emitted by many species of whales.

This type of sensory ability is not used by all whales (that we yet know of) but it is used by a variety of whales, most commonly all toothed whales species.

Toothed whales are able to produce a variety of high-frequency sound waves by moving air between the sinuses in the head area.

These sounds are then emitted throughout the water, where they then echo back from the different objects throughout the nearby areas of the ocean.

It is believed that an oil-filled area with the lower jaws of whales is able to receive this echo and feed it upwards to the middle ear of whales.

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