How does sound travel?

Sound travels as a wave of vibrations passing through a medium such as air, water or solid material. When something vibrates — like a guitar string or your vocal cords — it pushes on nearby particles, which bump into their neighbours and pass the disturbance along as alternating regions of compression and rarefaction. Your ear detects these pressure changes and your brain interprets them as sound. Because sound needs a medium to travel through, it cannot travel through the vacuum of space. Sound moves at about 343 metres per second in air, but far faster in denser media — around 1,480 metres per second in water and roughly 5,000 metres per second in steel.