Travelling sound

Sound spreads out and becomes quieter (lower amplitude vibrations) as it travels. Sound travels through a medium by vibrations being passed on between the particles of the medium. Sound travels faster through liquids than gases as the particles are closer so vibrations can be passed on more easily. Sound travels fastest through solids due to strong attractive forces between particles so many vibrate when one does. Sound waves are caused by vibrations of particles so sound can't travel through a vacuum (where there are no particles).