Can you hear sound in space?

Can you hear sound in space?

Space is vast, dark and [almost] completely silent. If you whisper, talk or even scream in space, nobody will be able to hear you!

Sound and other waves

To understand why this is the case, we need to understand the nature of sound. (And no, this is not very complicated, we promise)! Sound is a wave, a bit* like a wave you will see on the surface of a lake on a windy day.

*Strictly speaking, sound waves and water waves are two different kinds of waves. Sound waves are an example of a type of wave called longitudinal wave, while water waves are a type of a wave called a surface wave.

How sound works

Sound spreads out thanks to a medium – such as air, water or even solid things – that carries the vibration from the source to the listener. The Earth’s Atmosphere is made of different particles – nitrogen, oxygen, argon and some others. When we talk, sing, clap our hands, pull guitar strings (think about your favourite sound here), we push the air particles nearest to us. They begin to vibrate back and forth until they collide with and push their neighbours. Those particles begin to vibrate too and push on the particles closest to them and so on until these vibrations reach the ear drums of the person we are talking to. This is how sound waves spread out, or propagate. In the air, sound waves propagate at an impressive speed of 343 m/s* (767 mph). They travel even faster in the water, and faster still through the solid objects! Can an object move even faster and ‘overtake’ its sounds? Absolutely! We have an awesome post on the Speed of sound and what happens if you break the “speed limit” if you want to dig into the details!

* The exact speed depends on the characteristics of the air, such as its temperature and humidity. The above value refers to dry air at sea level and temperature of about 20 degrees C.

Hearing in humans and animals

Human ear is sensitive to a specific range of frequencies, although, of course, some people’s ears are more sensitive than others. This is called the AUDIBLE SPECTRUM, or hearing range. On average, a person’s ear can register a sound with a frequency (that’s how fast a sound wave is oscillating) between 20 Hz and 20 kHz. If a sound wave is oscillating fast, we perceive it as high-pitch, or high frequency sound. If a sound wave is oscillating slowly, we perceive it as low-pitch, or low frequency sound. 

Other species here on Earth are adapted to hearing sounds of higher or lower frequencies than humans. Bats, for example, hear high-frequency sounds between 20 and 200 kHz. Blue whales hearing, on the other hand, is adapted to low-frequency sounds from 10 Hz to 40 Hz. 

But let’s get back to space. Since space is mostly devout of matter, there is no medium for sound to propagate through. Therefore it simply cannot travel! We say MOSTLY, because actually there is gas and dust out there, spread out between planets and stars. All these gas and dust particles can, of course, carry sound. But because the density of this stuff is so much less than the density of the Earth’s air, your ear will not be able to pick up those vibrations anyway. 

But, hey, if you find yourself floating in the near-vacuum of space, under no circumstances should remove your space helmet to have a conversation! Why? Here are 5 reasons to keep your helmet and space suit on when going on a space walk!  

Do you have any other burning questions about Space?

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Author: Irina Vladimirova

Irina Vladimorova is a presenter at WonderDome Planetarium and a regular contributor to WonderDome Astronomy Blog. She holds a degree in Astrophysics and a special place in her heart for planetary science.