What is an echo?

Have you ever visited a hill station and shouted your name from the top just to hear it bounce back to your ears? Or visited a cave where shouting your name lets you hear your name multiple times? Well, all this is because of a phenomenon called echo which is what this very article is all about.

Echo:

  • An echo is a reflection of a sound that reaches a person’s ears after a short time delay from the actual sound. The delay is directly proportional to the distance between the reflecting surface and the source of the sound as well as the listener of the sound.
  • Sound is measured in decibel (dB).
  • Sound travels in waves and through the medium like air, water and wood.
  • When we say anything or make a sound inside a cave or on top of a hill, the sound waves generated by us travel through the air at different angles.
  • Some of these hit a particularly rough surface from which it bounces back to reflects. After a few seconds, we hear the same words said by us, but just a little bit fainter.
  • This change in the volume of sound is because as sound travels in different directions, it strikes a different surface which absorbs some of the vibrations i.e., the sound. Also, as the sound is reflected back to our ears, it has to travel through a long distance due to which the sound becomes faint.
  • Basically, echo stands for the repetition of sound heard by us due to the bouncing back of sound waves from any surface that reflects that sound.
  • When we speak something, sound waves are absorbed by our surroundings. That’s why we don’t all sounds do not create an echo.
  • The time taken by a sound wave to travel to the hard surface and return back to our ears depend on many factors and the most important one is the distance at which we are standing.
  • If we are standing near that surface, the turning echo will be faster as opposed to when we are standing a little farther.

Fun Facts:

  1. The human ear can hear sounds between 20-20,000 Hertz.
  2. The word “echo” comes from Greek mythology and has quite an interesting backstory. Echo was a Nymph who was responsible for talking to Hera while Zeus was having affairs with other women. as a way to distract her from the truth. However, when Hera found out, infuriated, she cursed Echo to only be able to repeat the things other people had said to her, for the rest of her life.
  3. Sound requires a medium to travel through. Hence, there is no sound in space as there is no medium available for the sound.

Related Questions:

  1. What is a sound wave?
  2. What is the speed of sound in different media?
  3. Is there any sound in space? Explain with reason.

True or False:

  1. Echo is the repetition or reflection of sound.
  2. An echo occurs when there is a hard surface.
  3. There is no change in the volume of a sound when it echoes.
  4. Sound does not require any medium to travel through.
  5. An echo is not heard when there is the complete absorption of sound waves by the surface.

Objective Quiz:

  1. Sound is measured in ________.
    1. Decibel.
    2. Litre.
    3. Meter.
    4. Voltage.
  2. Sound travels in _______.
    1. Waves.
    2. Particles
    3. Lines.
    4. Dots.
  3. Sound require _________ for travelling.
    1. Medium.
    2. Support.
    3. Path.
    4. None of the above.
  4. During a repetitive echo, there is a change in _________ of sound.
    1. Volume level.
    2. Words.
    3. Both 1) and 2).
    4. None of the above.
  5. Echo is generated when there is bouncing of sound from a ________.
    1. Rough surface.
    2. Soft surface.
    3. Clean surface.
    4. Movable surface.

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