Sound Wave Diagram — free printable diagram

What a sound wave diagram shows

Sound is made by something vibrating, and it travels as a wave through a material — a gas, a liquid or a solid. A sound wave diagram shows that wave in one of two standard ways: as rings spreading outwards from the source, or as a trace whose height and spacing stand for how loud and how high the sound is. Both are pictures of the same thing: a vibration being passed from particle to particle.

What makes a sound

A vibrating object

How it travels

As a wave through a solid, liquid or gas

Type of wave

Longitudinal — compressions and rarefactions

Amplitude

How loud the sound is

Frequency

How high or low the pitch is, measured in hertz (Hz)

Speed in air

About 340 metres per second

Cannot travel through

A vacuum — sound needs a medium

• A sound wave is longitudinal: the particles vibrate back and forth along the same direction the wave travels, squeezing together into compressions and spreading apart into rarefactions. Water waves and light are transverse instead, vibrating across the direction of travel.
• The particles themselves do not travel with the wave. Each one nudges its neighbour and returns, so the energy moves across the room while the air stays where it is — the single most useful point to draw out from the diagram.
• Amplitude is loudness. A bigger vibration shifts the particles further, is drawn as a taller trace, and is heard as a louder sound.
• Frequency is pitch. More vibrations per second means a higher note, drawn as waves packed closer together. Frequency is measured in hertz, one hertz being one vibration per second.
• Because sound needs particles to pass the vibration along, there is no sound in space. A bell ringing inside a jar gets quieter as the air is pumped out, which is the classic demonstration.
• Sound travels faster through liquids than gases, and faster again through solids, because the particles are closer together and pass the vibration on sooner.