By Ethan Mrs. Mann’s Class

Sound is created by vibrations. Vibrations are caused by something moving back and forth. Vibrations are too fast for you to see. Sound travels through energy waves called sound waves. No vibration makes no sound. When a string vibrates, it makes molecules of gases in the air next to it vibrate.

Sound waves travel through the air to get to your ear. Since sound can travel through air, it can also travel through gases. You can tell that sounds travel through solids by just putting your ear onto a tabletop. You can tell that sounds travel through liquids by going underwater and talking.

Pitch is sounds that are either high or low. To change the pitch on a stringed instrument you have to place one of your fingers on the string to make different sounds. Frequency affects pitch because when the frequency is high the pitch is also high, and when the frequency is low the pitch is also low.

Volume is how loud or soft a sound is. Energy affects volume by the sound waves having more energy to make it louder, or less energy to make it softer.

Reflection affects sound by bouncing the sound waves off of a hard surface. Absorption affects sound by absorbing a lot of the sound in smooth textured surfaces. One real-world example of reflection is when you scream into a piece of wood it will sound loud because the sound waves bounce off of the wood. One real-world example of absorption is when you scream into a pillow it sounds muffled because the sound is mostly absorbed into the pillow.

Echo is when you say something and the sound waves bounce off a surface and come back to you. One real-world place that can make echoes is the Grand Canyon. Another real-world example is if your in an underground cave. One more real-world example is when your in the shower.

Echolocation is when things or animals use sound waves to know what is around them. Bats use a form of echolocation instead of using sight. They send out high-pitched squeals and clicks into the air at their prey. Whales and dolphins also use echolocation. They bounce sound waves off objects to find out how far away they are.

The Doppler Effect is when a source of sound moves toward or away from you. One example of the Doppler Effect is when a police car speeds by you with the siren on. When the car comes closer the pitch is higher, and when it goes farther away the pitch is lower.

The End