What is Sound?

Physiologically, sound is a vibration in a medium once received by the ear. To achieve this you need three key elements.
1. a sound source
2. a medium for the sound to travel through
3. an ear to detect the sound

In the physical realm sound is a disturbance that creates the sensation of sound. By definition sound is a simple form of energy. When there is a series of disturbances in a medium, such as variations in pressure and alternations in direction of molecular movement the ear interprets that as sound. Sound is objective and therefore exists by definition regardless if there is any living thing to interpret it or be affected by it. So the answer to the old adage, “If a tree fell in the forest and no one was there to hear it would it make a sound?” is yes it would make a sound.