Was that sound high or low?

When you listen to sounds sometimes they are high and sometimes they are low. This is called their PITCH. This week the Year 5 and 6 classes investigated pitch to find out why some sounds are high and some are low. This is what they found out.

These are Boomwhacker tubes. When you hit them on the ground they make a sound. Each tube makes a different sound because they are different lengths. The air inside the tube vibrates.

Blowing into the bottles makes the air vibrate which produces a sound. Each bottle has a different amount of water in it. The bottle with lots of water and a little bit of air made a high sound. The bottle with a little bit of water and lots of air made a low sound.

The opposite happened when we tapped the bottles with a pencil. This is because when you tap the bottles it is the water that vibrates to make the sound and not the air.

Each test tube has a different amount of water in them so when you blow across the test tubes they make different sounds. When there is lots of air the sound is low pitched. When there is not much air the sound is high pitched.

These chime bars are different lengths so when you hit them they play notes of different pitch. When you hit the bars they vibrate to make the sound. The long bars play a low note and the short bars play a high note.

From doing these investigations we discovered that...

When the part that is vibrating is small the vibrations are closer together (high frequency waves) so the sound is high pitched. When the part that is vibrating is bigger the vibrations are further apart (low frequency waves) so the sound is low pitched.