We hear conversations, music and other sounds in everyday life.
However, sound is heard because of the presence of air, which cannot be heard in a vacuum.
This article explains in simple terms why sound cannot be heard when there is no air = in vacuum.
What is sound in the first place?
Sound is ‘vibration’.
Vibrations shake the air and other substances, causing waves to be generated and reach our ears.
Vibrations transmitted through the air cause the eardrums of the ears to tremble, which we hear as sound.
The height of sound is determined by how many waves(vibrations) arrive per second.
The sounds to be high when many waves arrive to our ears and it’s low in case of few waves.
Characteristics of sound
There are two types of waves, transverse and longitudinal, but sound is a longitudinal wave.
It is not that the air moves and transmits, but rather the vibrations are transmitted one after another as in a telephone game (Chinese whispers).
The sound is transmitted like a wave in cheering at a sport event.
The narrower the distance between the people cheering, the faster the waves are transmitted, and the wider the distance, the slower the waves are transmitted.
Therefore, transmission is faster in liquids and solids, where the spacing between the molecules that make up the substance is narrower, than in gases, where the spacing between air particles (molecules) is wider, such as in air.
This means that sound travels faster in water than in air.
Whales, for example, are said to communicate with each other by transmitting sounds underwater.
Why can’t sound be transmitted in a vacuum?
A vacuum is the ultimate state of thin air without any molecules drifting in the air.
In other words, in a vacuum, there are no molecules to transmit vibrations and therefore no sound is transmitted.
A vacuum not only prevents sound from being transmitted, but is also used in mechanisms such as membranes.
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