When sound waves travel through air, they cause the air molecules to vibrate. These vibrations create areas of high pressure and low pressure. The high pressure areas are called compressions, and the low pressure areas are called rarefactions. The compressions and rarefactions travel through the air at the speed of sound, which is about 343 metres per second at room temperature.

As the sound waves travel, the molecules that were compressed expand and the molecules that were rarefied contract. This creates more compressions and rarefactions, which continue to travel through the air.

The sound waves can be reflected, refracted, and absorbed. Reflection occurs when sound waves bounce off a surface. Refraction occurs when sound waves bend as they pass from one medium to another. Absorption occurs when sound waves are converted into heat energy.

The properties of sound waves can be used to create music, speech, and other sounds. They can also be used for medical imaging, navigation, and communication.