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Sound: Top 10 Questions

October 2012

Thanks to Steve Shropshire, Professor of Physics, Idaho State University; and Dr. Kathryn Levine, Assistant Professor of Physics, College of Idaho for the answers.

1: How are sounds made?

When you make a sound, you are giving a little bit of energy to the air around you. A sound wave is a compression wave of all the molecules in the air that carry that energy from whatever made that sound to your ear. (From Jack at Shadow Hills Elementary School in Boise)

2: How fast and how far does sound travel?

At room temperature, sound travels at around 330 meters per second. It's quite fast. Sounds can travel great distances. A volcano near Indonesia exploded back in the 1800's. The sound was heard for hundreds of miles. That was through the air. Sound travels a little bit better through water. Whales can communicate with each other over hundreds of miles of ocean. (From Shelbe at North Star Charter School in Eagle)

3: Why does sound travel in waves?

A wave is a disturbance. If you push on something, like a table, you expect the whole table to move. With air or water, when you push on one part of it, it takes a while for that disturbance to move as it doesn't move all at once. It is more fluid. Like when you throw a rock in water, you can see the waves that the rock created. Air moves the same way. (From Noah at Dalton Elementary School in Dalton Gardens)

4: How does sound travel through space?

The same thing that happens on Earth happens in space. One molecule communicates the wave to the next. The difference is that in space the density of the air is a lot lower meaning the molecules are further apart. As long as there is gas or molecules in space, sound can travel. If there isn't anything, then sound can't travel. (From Alyssa at Whitman Elementary School in Lewiston)

5: Why do a trumpet and a saxophone sound different, even when they are playing the same note?

It has to do with how the sound resonates in the instruments. Longer and bigger instruments make lower sounds. Shorter and smaller instruments make higher pitched sounds. (From Braden at Lena Elementary School in Moscow)

6: How does sound travel better through water?

Water is denser than air. There is more stuff in water in a smaller space. The molecules are closer together. When molecules in water get a disturbance or energy from sound, they collide with other molecules more rapidly. Also, water is more elastic than air. All of this contributes to making the sound travel better and farther. (From Sarah in at Saint Mary's Elementary School in Moscow)

7: How far can a fire alarm sound travel?

It depends on the fire alarm. The amount of energy that is produced, or the volume of the alarm, dictates how far the sound will travel. The louder the alarm, the further it's sound will travel. Large apartment buildings may have very loud alarms and they could be heard from further away. Smaller alarms, like those in the schools, may not be as loud and nearby houses may not hear them. (From Shaun who is homeschooled in Illinois)

8: How many animals use sound to navigate their way around the world?

Bats use sound to navigate and to hunt. They actually listen very closely to the sound that bounces off of insects and objects around them. A lot of fish and ocean creatures also use sound to navigate and hunt. Even some birds use sound. (From Cameron at Dalton Elementary School in Dalton Gardens)

9: Why can't you see sound waves?

A sound wave is a little tiny molecule that you can't see. You can't see the air even though there is stuff in the air. The small things in the air transmit the sound. They are all so tiny that we can't see them. (From Matilda at Dalton Elementary School in Dalton Gardens)

10: How fast do you have to go to break the sound barrier?

The speed of sound is 330 meters per second at room temperature. So that's about how fast you would have to go. (From Alex at Paramount Elementary School)


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