1. Why Is There No Sound in Space?
Sound waves need a medium to travel through. Here on Earth, sound can travel due to air molecules vibrating and hitting each other. When the air particles reach our eardrums, the vibrations send signals to our brain and that’s how we interpret sound.
Space, however, is a vacuum and has no molecules. Because of this, it’s impossible for sound to travel through it. Space is vast and completely silent. That’s why astronauts go through a lot of training in anechoic chambers before setting off for space. It gives them a chance to get used to sitting in complete silence without losing their minds.
Now, you may be wondering how astronauts are still able to communicate in space. It’s simple. They use radio waves. These types of waves can travel through a vacuum because they are electromagnetic waves just like light and they don’t require a medium to travel through.
2. How Sound Travels
The speed of sound depends on the temperature of the medium it travels through. The generally accepted speed of sound is calculated at a temperature of 20° C (68° F) and it is:
- 343 m/second
- 1,235 km/h
- 1,125 ft/s
- 767 mph.
It travels even faster than that in water, at speeds of 1,482 m/second. That’s why sea lions can hear much better underwater than on land.
Sound travels fastest through steel (4,512 m/second) because the particles of steel are closer together and more stable than air.
Although this speed is amazing, sound travels slower than light. This is why, in a thunderstorm, you will see the lightning sooner than you hear the thunder.
3. What Is the Loudest Natural Sound?
The loudest possible sound traveling through air is calculated at 194 dB. This is due to the fact that how loud a sound is will depend on the amplitude of the sound waves compared to the ambient air pressure and any sound over 194 dB would cause the sound waves to create a complete vacuum between themselves.
However, sounds much louder than that were produced in 1883 by the eruption of a volcano on the Indonesian island of Krakatoa. The loud boom was heard as far as 4,800 km (3,000 miles) away and people that were 3,110 km (1,930 miles) away in Perth, Australia reported hearing very loud sounds similar to artillery. The sound waves travelled much further.
The sounds of the volcano eruption were picked up by measuring instruments located 160 km (100 mi) away. They recorded levels as high as 172 dB from that distance. Scientists believe the Krakatoa eruption is the loudest sound humans have ever accurately measured.
The sound of the boom was so powerful that it traveled around the world multiple times. It wasn’t heard everywhere, but changes in atmospheric pressure caused by the explosion were recorded as far as Toronto and St. Petersburg. The sound of the blast was estimated at 310 dB.
4. Horror Movies Use Infrasound
Have you ever wondered how horror movies manage to scare us so much even though we know they are make-believe?
It’s actually because of infrasound. Filmmakers use it because it is low-frequency and outside the human hearing range but has great fear-inducing effects. Infrasound can create anxiety, and shivering, or heart palpitations.
5. There Is Such a Thing as Fear of Music
It’s hard to imagine anyone could dislike music, let alone fear it. Still, there is such a phobia. It’s called melophobia (from the Greek word “melodia”, meaning music).
This type of fear is triggered by a negative event in a person’s life that causes negative emotions linked to the sound of music. Therefore, the person suffering from this phobia may be unable to listen to some types or any type of music. Symptoms can include shortness of breath, elevated heart rate, dizziness, nausea, anger, and inability to think clearly.
Melophobia can reduce a person’s ability to socially function, as music is all around us, in elevators, stores, on TV.
6. Animals and Sound
Dolphins are well known for their good hearing and communication abilities. It is true that they can hear ultrasounds and use echolocation to read their surrounding environment.
Bats are also known for their use of ultrasound to read their environment and their high-precision hearing abilities. Scientists have found bats are able to hear sounds that vibrate up to 200,000 times/second.
Foxes are a lesser-known animals with extremely good and precise hearing. They are said to be able to hear a mouse squeaking or scratching over 100 m (330 feet) away, even when the mice are underground.
Birds use sound to make ‘sound maps’ that help them navigate in their migrations.
As for the loudest animals, blue whales were thought to produce the loudest sounds in the animal kingdom, estimated at 188 dB. Now, the pistol shrimp is in the spotlight. It is a small type of shrimp that has an unusually large claw. When the creature snaps the claw shut, it generates an intense sound that stuns its prey. The sound of this stun gun the pistol shrimp uses is estimated at 210 dB.
7. Breaking the Sound Barrier
The speed of sound is referred to as Mach 1. Any speed over the speed of sound is known as supersonic. Jets that can travel at a speed of Mach 1 need to break through the sound waves that press the air in front of the plane. When they do, the explosion-like sound that is produced is referred to as a sonic boom.
The Mach scale indicates how many times the speed exceeds that of the speed of sound. For instance, Mach 5 is five times the speed of sound and known as hypersonic sound.