When a sound becomes dividing from its unique sound and is repeated due to reflection then this reflected sound is called echo. Theoretically, an echo is the sound you hear when you make a noise and the sound wave reflects off a secluded object. So, when a sound wave is formed in the air, some of it is absorbed after beating with a reflector while some of the sound waves are reflected reverse to the listener. This reflected sound is called echo.
Uses of Echo –
Determination of the depth of a well:
Depth of water surface of a well can be very easily determined by means of echo. When a sound is produced at the mouth of the well, it is reflected from its water surface heard in the form of an echo. The time between the production of sound and the hearing of echo is determined by means of a stopwatch.
Let, depth of well = h
the time difference between the production of sound and hearing of echo = t
Speed of sound = v
Now the distance traveled by reflected sound to the listener is 2h.
Therefore, 2h = V x t
or, h = (V x t)/2, If the depth of the well is less than 16.6m, it will not be possible to perform this experiment as it is based on echo.
In the same way, this method can also be used to find mineral substances on earth.
Flying of the bat:
Bat flies using the echo of sound as it cannot see. Bat can produce and hear an ultrasonic sound. We cannot hear ultrasonic sound Bat produces ultrasonic sound and spread it forward which reflects back to the bat from a reflector. Bat can understand from the reflected sound if there is an object before it. It hunts its prey using this technique. If the sound does not reflect back then it can understand that there is open space and it flies that way. Sometimes the bat fails to detect the position of wires of electric lines and flies through the parallel wires and gets stuck and becomes dead as soon as the positive and negative electric lines get connected with its body. This is why sometimes bats are found hanging dead from electric lines.
Since bats cannot see from their eyes, so they use the method of echolocation to situate their ways. Bats can understand from the reflected sound if there is an object before it. It hunts its prey by using this system. They emit ultrasonic waves, which are reflected from the obstacle and help the bats in avoiding them.
Bat can produce and hear the sound of frequency about 1.00.000 Hz.
By knowing the velocity of sound and measuring the time it takes to hear the echo, you can estimate the distance of the object. Echo is used in SONAR (Sound Navigation and Ranging) to find the depth of seas or distance of submarines. The principle used here is the fact that time taken for the sound to reach the obstacle from the source is equal to the time is taken for it to return.
A sonar device sends out a sound and mechanically calculates the distance of an object. Submarines use sonar to find objects under the water, including other submarines.
Echo is used by doctors in a technique called echocardiography in which ultrasonic waves are made to reflect from various parts of the hearts and from an image of the heart. Doctors used this occurrence in cardiography, sonogram and many other medical diagnoses. It is also used in medical procedures to assess for blockages in the heart for example.
Other Common Applications of Echo:
- This technique is also used to find the depth of sea or distance of submarines.
- It is particularly useful in mapping the depth of the ocean and also finding lost objects at sea.
- It also helps to estimate the distance or hills and mountains.