We can hear sounds because our ears turn sound vibrations from the air, into signals that are sent to our brain. We can’t hear all levels of sounds. Sound waves with very high frequencies are called ultrasound and our ears can’t detect them.

Sound waves enter the outer ear and travel through a narrow passageway called the ear canal, which leads to the eardrum. The eardrum vibrates from the incoming sound waves and sends these vibrations to three tiny bones in the middle ear. These bones are called the malleus, incus, and stapes.

Usually air molecules create quiet sounds and small movements that we cannot hear or feel. But when something creates a strong enough vibration, like when someone claps their hands or when your vocal chords move when you talk, the air molecules get pushed into each other. This causes a wave of sound to travel through the air.