A sound source emits sound waves in all directions through the medium. The wave expands losing intensity as it travels away from the source. This energy loss is quite rapid as the distance from the sound source increases.

When sound waves reach our ear, they move on through the ear canal towards the eardrum, which is at the end of the ear canal, and make it vibrate. The vibrations of the eardrum continue into the middle ear, where there are three tiny bones. The vibration of these bones brings the sound waves to the inner ear. Here the vibrations are changed to a signal. Through a nerve the signal is sent to the brain which interprets the message to us – this is how we hear.