A hearing (audiometric) test is part of an ear examination that evaluates a person's ability to hear by measuring the ability of sound to reach the brain.
The sounds we hear start as vibrations of air, fluid, and solid materials in our environment. The vibrations produce sound waves, which vibrate at a certain speed (frequency) and have a certain height (amplitude). The vibration speed of a sound wave determines how high or low a sound is (pitch). The height of the sound wave determines how loud the sound is (volume).
Hearing happens when these sound waves travel through the ear and are turned into nerve impulses. These nerve impulses are sent to the brain, which "hears" them.
- Sound waves enter the ear through the ear canal (external ear) and strike the eardrum (tympanic membrane), which separates the ear canal and the middle ear.
- The eardrum vibrates, and the vibrations move to the bones of the middle ear. In response, the bones of the middle ear vibrate, magnifying the sound and sending it to the inner ear.
- The fluid-filled, curved space of the inner ear, sometimes called the labyrinth, contains the main sensory organ of hearing, the cochlea. Sound vibrations cause the fluid in the inner ear to move, which bends tiny hair cells (cilia) in the cochlea. The movement of the hair cells creates nerve impulses, which travel along the cochlear (auditory, or eighth cranial) nerve to the brain and are interpreted as sound.
Hearing tests help determine what kind of hearing loss you have by measuring your ability to hear sounds that reach the inner ear through the ear canal (air-conducted sounds) and sounds transmitted through the skull (bone-conducted sounds).
Most hearing tests ask you to respond to a series of tones or words. But there are some hearing tests that do not require a response.