How it's made, changed and heard
How is sound made?
Sound can be made from our voice, instruments, loudspeakers....etc. When the vibrations are travelling through the air, they are called sound waves. Sounds are also very different. It's due to the molecules that vibrate in the air, that the sound can travel.
For example: A piano can play a high sound but a low pitch by playing quitely on the notes and using the pedal.
Another example is that if you are talking quitely then you could also talk with a very deep pitch.
How is sound changed?
Sound can be changed in several ways. It can be changed by having a low pitch or a high pitch. You can also change the sound by having a low or high amplitude. The loudness of the sound also differs from instrument to instrument. Some instruments have high pitch while others have the opposite.
How is sound heard?
We hear sound when our inner hear is hit by vibrations. The ear is made of several parts that vibrations need to get through in order to allow us to hear sound. Vibrations go inside our ear and hit our three small bones where their vibrations hit our cochlea that then allows us to hear what other people are saying. Although some people are born without those three small bones. These people are deaf since the vibrations cannot travel through the ear because there are no bones for the sound vibrations to hit. Some people have higher frequencies than others which means they can hear from a larger distance. This means that we can also hear sounds that we don't want to hear which is called noise. Bats are a very special animal since they can't see but they can still find their way around. It makes it own vibrations which then reflect on the object and are send back to him to tell the bat how far away he is from the object.
This is the object you use for mesuring sound waves. There are high pitch, low pitch, high sound and low sound that are showed on a oscilloscope to see the loudness or pitch of the sound vibrations. You can use this for your voice vibrations and instrument vibrations.
-Cambridge Checkpoint Coursebook For Year 8s