11 Sonic Facts about the Speed of Sound

First published 8th February 2024 Samantha Khu

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As kids, we all want to think that we can run at the speed of sound! Who hasn’t put on their fastest shoes and tried to break the sound barrier? If you haven’t tried it, you absolutely should. But what exactly does the speed of sound mean, and how does it work? Here are some fun facts about the speed of sound!

1. The speed of sound actually refers to distance.

The speed of sound can be defined as the distance that’s traveled per unit of time by a sound wave as it navigates its way through a medium, which is usually air. The speed of sound can often vary depending on the type of medium through which it’s actually traveling. It is faster in denser mediums and slower in less dense ones.

2. Speed usually travels a few feet per second.

In the right circumstances, i.e., in dry air at sea level and at a temperature of 20 degrees Celsius (68 degrees Fahrenheit), the speed of sound is agreed to be roughly 343 meters per second (equivalent, therefore, to 1,125 feet per second).

3. Temperature changes the speed of sound, too.

Believe it or not, temperature also impacts the speed of sound! For example, in warmer air, sound waves travel faster.

4. Altitude also has an impact on the speed of sound.

The speed of sound also changes with altitude. For example, at higher altitudes, where air is less dense, sound waves travel more slowly.

5. It can be expressed in Mach.

You may have heard of the speed of certain objects as traveling at “Mach” something. That is because the speed of an object is often detailed as the Mach number, which is the ratio of the object’s individual speed to the speed of sound in a medium.

6. Some things go supersonic, while others go subsonic.

Any object traveling at a speed greater than the speed of sound is said to be supersonic. On the other hand, an object traveling at a speed slower than the speed of sound is subsonic. You’re either one or the other, then!

7. Some objects can create a sonic boom

The term “sonic boom” refers to more than just an extremely fast hedgehog. Sonic boom also refers to when an object travels through the air at speed faster than the speed of sound – it creates a deafening shockwave.

8. Water can help the speed of sound.

Strangely, sound actually travels much faster in water than in air! In seawater, sound travels at an average speed of about 1,480 meters per second – that’s 4,855 feet. That’s also pretty impressively – and seemingly impossibly – fast!

9. There is no sound in space.

Space is completely quiet. This is because sound cannot travel through its vacuum. It requires a medium (such as air, water, or a solid substance) to transmit waves. Remember what the poster for Alien said – in space, no one can hear you scream? Or whisper, or sing, or…

10. The speed of sound is extremely useful.

Oddly enough, the speed of sound has tangible use in various ways. The speed of sound has been used historically as a method for measuring distances. By timing how long it takes for sound to travel, one can calculate the distance to an object.

11. Sound travels fast in helium, too!

Sound also travels faster in helium than in air because helium is less dense than air. This is why voices sound higher-pitched when helium is inhaled! While it’s fun to make those noises, try not to breathe in too much of it!