Sonar Wave: Definition, Types, Properties and Uses Explained

Sonar Wave is a pulse of sounds used by vessels and marine life to navigate, communicate and detect objects underwater. Sound waves can travel very well through water and this is the reason sailors and explorers use Sonar Waves to detect the underwater objects and the distance between their ship and them. Long before humans discovered Sonar Waves animals such as bats, dolphins and whales were using their biological Sonar to detect invisible distant objects on land and underwater. This natural ability of animals is termed as echolocation. This fascinating sound wave is also used in medical diagnostics for imaging our organs. Let’s explore interesting facts about Sonar Waves and their functioning along with types and uses.

Table of Contents 

• What Is a Sonar Wave?
• How Does Sonar Work?
• Types of Sonar Waves
• Applications of Sonar Wave
• Interesting Facts About Sonar Wave

What is a Sonar Wave

Sonar short for sound, navigation and ranging is a high frequency sound wave (above 20,000 Hz). It helps in mapping objects under the surface of water and also enables submarine vessels to communicate with each other. These high frequency sound waves are also called ultrasound that navigates at a speed of about 1500m/s and echoes back after hitting an object in water. 

A Sonar device on a ship sends out the Sonar Waves in water which then bounce back and send a signal to the receiver. The amount of time it takes for the wave to bounce back is detrimental for the distance between the object and the ship. It helps sailors to safely map and navigate throughout the ocean. We‘ll understand the working principle of Sonar Waves in detail in the next section.

How does Sonar Work

The Sonar works on the simple principle of how long the sound bounces back after hitting an object under water. It is the same as a voice echoing in a tunnel. The light cannot travel under water very well so we use a Sonar device to explore oceans. A Sonar device sends out the Sonar Waves into water through a transmitter. The waves transmitted into the water, bounce back after hitting objects like rocks, fishes, ocean floor or wrecks of sunken ships. A receiver on the device listens to these waves and helps detect where and how far these objects are placed inside the surface of water. The time it took for sound to echo back helps us in determining the distance at which the object is from the ship. 

Scientists use a formula based on the time taken and the speed of sound to calculate exactly how far away the object is. The formula is: 

Distance = (Speed of Sound × Time) ÷ 2

For example, if a Sonar travelling at the speed of 1500 meter per sec (1500m/s) pings back in 2 sec, then the distance will be: D = (1500 x 2) ÷ 2, which means it is 1500 meter or 1.5 km away from the device.

Types of Sonar Waves

Depending on what needs to be determined Sonars are classified into active and passive Sonar Waves:

Active Sonar Wave: An active Sonar emits a sound pulse in water and receives the sound signals from the echo. It is helpful in determining the exact distance and direction of objects underwater. These types of Sonar Waves are used in ships, submarines, and scientists to map the ocean floor.

Passive Sonar Wave: This type of Sonar Wave is used to only listen to noise from marine objects or marine animals. Underwater microphones called hydrophones do not emit signals but pick only noise coming from the other marine vessels, Sonar equipment, sharks or whales. Whales and other animals emit a natural Sonar that can be detected using passive Sonar. These are also perfect for military use to detect other marine equipment or vessels without getting detected.

Applications of Sonar Wave

• Military Operations: Passive Sonar Waves are used for detecting enemy submarines in the ocean during war or military operations as it helps to locate other ships without getting detected.

• Commercial Fishing: Fishermen use Sonar Waves to locate the schools of fishes for catching them efficiently.

• Measuring Depth of Ocean: These waves are used for mapping depth of the ocean floor called depth sounding.

• Calculate the Distance: It helps marine vessels and sailors to locate objects and calculate distance between them.

• Safe Navigation: They help ships in navigating safely in water and locating sunken ships and archaeological sites underwater.

• Medical Imaging: Sonar Waves or ultrasounds are also used for diagnostics by creating imaging of organs inside the body.

Interesting Facts about Sonar Wave

• Leonardo Da Vinci was the first person to use Sonar Waves. He placed a pine in water to hear the noise from other ships.
• The wreck of the Titanic ship was found after 75 years of sinking in the year 1985 with the help of Sonar Waves.
• Bats use their biological sonar to see their surroundings in the dark. They can even detect thinnest objects like human hair with complete accuracy in darkness. 
• Lewis Nixon invented the first Sonar-type listening device to detect icebergs in 1906.