Test Overview
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
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
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.