The loudness of a sound is dependant on the amplitude of a wave (the height of the wave). The taller the wave, the louder the sound made.
The pitch of a sound is dependant on the frequency of a wave (the number of waves per second). The higher the frequency, the higher the pitch.
When you play a musical instrument, you create sound waves by making the instrument and air inside it vibrate. Each new cycle of vibrations makes the vibrations stronger at certain frequencies. We say the instrument resonates at these frequencies. Because the instrument and the air inside it vibrate strongly at these frequencies when it is played, we hear characteristic notes of sound from the instrument.
- A wind instrument such as a flute is designed ao that the air inside resonates when it is played.
- A string instrument such as a guitar produces sound when the strings vibrate. The vibrating strings make the surfaces of the instrument vibrate and produce sound waves in the air.
- A percussion instrument such as a drum vibrates and produces sound when it is struck.