What is sound?

Sound is a form of energy. Sound waves are compressional waves. A sound wave moves through matter, such as air, just like a wave moves through a slinky. Unlike light waves, sound waves do not travel through a vacuum. They need matter to travel. That is why sound can travel through a wall.

 

What happens when we hear a sound?

An object like a violin vibrates the air, and those vibrations travel from the violin through the air until they reach us. But we don't hear a violin with our noses or our elbows! These vibrations need to travel into our ears for us to really hear them.

 

Sound Waves

Pitch is how high or low a sound seems. A bird makes a high pitch. A lion makes a low pitch. Sounds also are different in how loud and how soft they are.

 

The more energy the sound wave has, the louder the sound seems. The intensity of a sound is the amount of energy it has. You hear intensity as loudness. Remember the amplitude, or height of a sound wave is a measure of the amount of energy in the wave. so the greater the intensity of a sound, the greater the amplitude. Pitch and loudness are two ways that sounds are different. Another way is in quality.

 

Some sounds are pleasant and some are a noise. A pleasant sound has a regular wave pattern. The pattern is repeated over and over. But the waves of noise are irregular. They do not have a repeated pattern.

 

Task

Write down the new vocabulary in your language as well.