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Why does talking in an empty room have an echo?

Sound in an empty room will echo because there is nothing stopping the sound waves from being reflected between hard surfaces like walls, windows, ceilings and floors. Since not all materials reflect sound well, the energy of the sound waves is absorbed by the surfaces. However, sound will continue to be bounced between hard surfaces until it loses energy.

Explain why talking in an empty room has echoes

What is the echo?

If you are facing a flat wall and snapping your fingers, the snap will hit your ears twice. The first time was the sound coming directly from the snap. And the second time was the indirect sound. The snap will go from your hand to the wall, be reflected back then to your ears.

Since the second snap is longer traveled, it will take longer for you to hear it. So you will first hear the sound coming from your hand first. Then a second snap was reflected back from the wall.

If the lag between the two sounds is loud enough, you will hear the second snap like an echo. As noted above, the resonance will usually be less than the sound directly reaching your ears. The larger the room and the higher the ceiling, the more different the two sounds will be. But for the rooms in the house, they are only called reflected sound.

What resonates in the room?

In an empty room with flat walls, ceilings, and floors, sound bounces back and forth between surfaces. Surfaces made of glass, stone, brick, mortar, and wood all have excellent reflectivity and will increase the number of reflections of sound. Thanks to that, the sound in the room will become more vivid.

Each room will have many different “types” of sound reflection. Types differ in the way sound is reflected in space. There are three types: axial, tangential and oblique.

Axial is the simplest type. Sound reflected between two opposite surfaces such as between the ceiling and the floor or between two walls …

Tangenxial is the type of sound reflected through four surfaces around the room. Four surfaces can be four walls or 2 walls and ceiling, floor.

If the room you are standing in has a high ceiling and a great length, the echo in that room will last very long. So that’s why too long rooms or too high ceilings can cause some echo problems.

You can only hear echoes in large rooms, for example in halls or in churches. The reason is that the human ear has limitations in hearing.

Our ears cannot distinguish the original sound from its echo if the delay between two sounds is less than 0.1 seconds. If the sound reflected to the ear after the original sound is less than 0.1 second, we will hear the reflected sound overlap the end of the original sound but slightly less.

If sound is constantly bouncing between surfaces in the room, a series of echoes are heard. The echoes will overlap and gradually diminish. The sound will continue to appear and gradually disappear.

The sounds you hear after the original sound are reflected. So, for the rooms in the house, we cannot distinguish individual echoes because the distance between the reflected sound and the original sound is less than 0.1 seconds.

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