The ear and hearing
Ears are extraordinary organs, and hearing is an extraordinary ability. Hearing is mostly a mechanical process and based on physical movement. The sound you hear are pressure waves travelling through the air producing vibration, responsible for the pitch (higher or lower sounds), and amplitude (louder or softer sounds).
The human ear
How the human hearing works
The ear directs sound waves down the auditory canal to the eardrum, causing it to vibrate slightly. The ossicles work together as a lever system; they amplify the vibrations and pass them on to the surface of the cochlea in the inner ear. This physical vibration creates compression waves within the fluid-filled spiral tube of the cochlea, which then move the tiny hair cells. At their base this movements create a motion which is changed into electrical signals. These can now be processed by the central auditory system and be interpreted as sounds like speech, music, or noise.
The human ear is composed of:
- The outer ear, responsible for capturing and directing sound waves through the ear canal to the eardrum. It consists of the pinna and the auditory canal.
- The middle ear, where the three ossicles (hammer, anvil and stirrup, the smallest bones in the human body) transfer the vibrations from the eardrum (tympanic membrane) to the inner ear.
- The inner ear, where the cochlea (with 15 000 hair cells) transforms the mechanical waves into electrical signals which are processed by the brain.
