The age-old question – can anyone hear you scream in space? Short answer – no! But why? To find out more about this, let’s take a look at how sound is produced, why we hear it the way we do on Earth, and why we can’t hear sounds in space!
Read on to find out more about this somewhat spooky to think about phenomenon!
What Is Sound?
Sound is an elastic wave that travels through air or any other medium at high speed. It is created by pressure changes which are caused by vibrations of molecules in the medium.
These vibrations are called acoustic waves and they travel at the speed of sound.
This means that if there was no medium around, then the sound would not be able to travel very far. If the medium were water, for example, then the speed of sound would be 1,350 m/s (1,500 mph).
However, when sound hits an object such as a wall, it slows down because the walls have mass.
If you’ve ever tried to shout something to someone in another room, you’ll notice that your voice is muffled – that’s because those soundwaves have to travel through more mass before they can be picked up by your friend’s ears in the next room.
This causes the frequency of the sound to change and it becomes lower than the original frequency. When the sound reaches our ears, the ear picks up these low frequencies and converts them into higher ones.
This process is known as transduction.
How Do We Hear Sounds?
When sound waves hit our eardrums, they cause tiny hairs in our middle ear to vibrate. These hairs are called the cochlea and they act like tuning forks.
They bend back and forth with the vibrations of the sound waves. The bending of the hair cells sends signals to the brain where they are interpreted as sound.
In addition, the lack of gravity also affects the way we hear things. For instance, the pitch of a note is determined by the length of time between two notes. On Earth, this is due to the pull of gravity causing objects to fall towards the ground.
However, in space, the pull of gravity is absent so objects don’t fall downwards. Instead, they float around freely. Because of this, the length of time between notes stays the same and the pitch doesn’t change.
If you imagine a visual representation of a wobbly sound wave, gravity is keeping that vibrating wave stable enough that it can be heard.
Without gravity and mass to move through, however, the wave can never start and has no path, so it can never be heard.
Why Does My Voice Sound Different Underwater?
Because sound waves travel through water at a faster rate than they do through air, water is a better conductor of sound.
Sound waves travel through the air at different speeds depending on their frequency. This should make the sounds seem louder underwater.
When you’re not submerged, you might perceive it as softer than it is. Because the water surface is almost a mirror for the sound that you create, it sounds softer than it is.
The sound was almost completely reflected into the water, bouncing back as soon as it hit the surface.
If you only immersed one ear, the sound probably would still appear muffled. This happens because the ear evolved to pick up sounds in the air, so it doesn’t work well when there’s water between the ear and the source of the sound.
When you submerged your ears, the sound probably sounded deeper. That’s, in part, because our heads contain a lot of water, allowing the tissues to pick up underwater sounds without relying on the eardrums.
It also explains why not closing your ears makes almost no difference in hearing when you’re underwater.
Another reason things sound deeper underwater is that low frequencies travel further in water than high frequencies, meaning, after a certain time or distance, only the bass notes remain to be heard.
Underwater sounds stay underwater because very little sound passes from the water to the air. If you’re not listening when your head is underwater, you won’t be able to hear anything.
You may think it’s weird that you can hear reasonably well underwater, but not in space, which is seemingly more akin to air, the medium through which we hear best of all, but there’s a very logical explanation.
Why Can’t We Hear Sounds In Space?
So why can’t we hear anything in space? Well, first off, we need to understand what makes us hear sounds in the first place.
As we mentioned above, the reason we hear sounds is because of the vibrations of the air molecules. In space, however, there isn’t any air. There is only a vacuum. Vacuum is basically another word for ‘nothingness’.
Because there is literally no way for sound waves to travel, as there is no air, no sounds can be heard. The reason why we don’t hear anything in space is that there is no atmosphere to transmit the sound waves.
Without an atmosphere, sound doesn’t exist. There is no air to cause the pressure waves to move, and therefore there is nothing to make us hear the sound.
Why Do We Hear Sounds Differently In Space?
When we talk about hearing sounds, what we really mean is picking up vibrations from the air. On Earth, these vibrations are picked up by our eardrums and converted into electrical signals.
Our brain then interprets these signals as sound. However, in space, there is nothing to carry these vibrations or sound waves. There is no air, so there are no vibrations.
What About The Space Roar?
Whilst you can’t hear sound in space, as there is no way of the waves being carried to our ears, it is possible to pick up sounds on Earth from the universe around us with the right equipment!
Back in 2006, scientists used a complex piece of equipment called the ARCADE (Absolute Radiometer for Cosmology, Astrophysics, and Diffuse Emission) instrument to record the noise of the cosmos. They found that the universe has its unique sound, which they named the ‘space roar’.
It turns out that this sound is caused by supernovas, exploding stars that emit huge amounts of energy. These explosions send shockwaves through the surrounding gas and dust, creating ripples in the fabric of space-time itself.
This ripple in spacetime causes a disturbance in the electromagnetic radiation traveling through space. ARCADE was able to measure it!
As the instrument listened from a height of around 40km, it picked up a signal that was six times louder than what was expected by leading scientists and astrophysicists.
Because it was so loud, it could not be an early star, and its power was far greater than the expected combined radio emission from distant galaxy clusters. And scientists still don’t know what is exactly causing it, even today!
Because light travels so much faster than sound, and from Earth, we are still witnessing events in the sky that are so far away that they occurred millions of years ago, it is easy to imagine that these noises we are picking up are eons old!
So If We Can’t Hear Sound In Space, Why Can We Hear It On Earth?
Sound doesn’t exist in space, well not in the sense that we can experience it on Earth. Sound travels through the vibrations of particles, and space has no air.
Sound waves travel in what’s called longitudinal waves, which means they cause back-and-forth vibrations of the particles in the material through which they are traveling.
On Earth, this sound travels through a medium at the rate of sound speed, which varies depending on the substance.
Generally, it moves slower through gases than liquids, and fastest through solids. Humans can usually hear sound within a narrow range of frequency, usually between 20 Hz and 20,000 Hz.
We’re fortunate we can only pick up this narrow range of frequency because otherwise, the sound of the Sun roaring at an impressive 100 decibels would be deafening to us here on Earth – like listening to a rock concert all day every day.
With the power of modern technology that is far more sensitive to the almost impossibly slow frequencies that sound waves travel via space debris, you can find recordings of the eerie space noises all around our universe!
We highly recommend giving them a listen, the haunting and robotic sounds are indescribable!
No, as human beings, we are unable to hear in space due to the lack of atmosphere to funnel sound waves to our eardrums.
However, with the power of incredibly advanced machinery, we can transfer the radio waves and frequencies of various space oddities into sound waves that are of a frequency possible to be picked up by the human ear.
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