A material medium is required for sound as sound cannot travel through a vacuum.
The energy of the vibration is transmitted through the material medium and causes a vibration of objects at a distance.
Sound travels through all material media – solids, liquids and gases. Sound travels through a solid medium faster than a liquid medium but slower in a gas.
Sound waves travel as longitudinal waves - Compressions pulses (High Pressure) and - Rarefactions pulses (low Pressure)
Interference provide us with further evidence that sound is transmitted as a wave - Constructive interference - sound gets louder - Destructive interference - sound gets softer
