1.A sound is created when the particles in a medium (usually air in our world) are set moving and forced out of a state of rest. This happens, for example, when we speak. Our vocal chords produce audible pressure variations (high and low pressure) in the air. Sound travels in air at a speed of approximately 340 metres per second. It spreads like a wave and is a mechanical vibration.
2.Sound is a type of energy made by vibrations. When any object vibrates, it causes movement in the air particles. These particles bump into the particles close to them, which makes them vibrate too causing them to bump into more air particles. This movement, called sound waves, keeps going until they run out of energy. If your ear is within range of the vibrations, you hear the sound.
Picture a stone thrown into a still body of water. The rings of waves expand indefinitely. The same is true with sound. Irregular repeating sound waves create noise, while regular repeating waves produce musical notes.
When the vibrations are fast, you hear a high note. When the vibrations are slow, it creates a low note. The sound waves in the diagram show the different frequencies for high and low notes
3.music