A sound wave is a transfer of energy as it travels away from a vibrating source. Sound waves are formed when a vibrating object causes the surrounding medium to vibrate. A medium is a material (solid, liquid or gas) which a wave travels through. As sound waves move through a medium the particles vibrate forwards and backwards. A sound's volume, how loud or soft it is, depends on the sound wave. The more energy put into making a sound or a sound wave, the louder it will be. The farther a sound wave travels, the more it spreads, this makes it more difficult for us to hear a distant sound. So the nearer we are to a sound the louder it sounds to us. A sound wave enters the ear and is changed into nerve signals, which are interpreted by the brain.
