An audiometer is an instrument used to measure how well a person hears during a basic hearing test, called an audiogram, which tests the ability to hear pure tones in each ear.The ear, a complex organ, receives sound in the form of vibrations that strike the eardrum. These vibrations move from the eardrum through the bones of the middle ear to the cochlea, a spiral-shaped organ filled with fluid. The vibration sets the fluid in motion and sensory cells along the cochlea's basilar membrane send messages of the sound to the brain. A complete audiogram tests bone conduction--the ability to hear sound transmitted through bone, and air conduction--sound transmitted through air. Comparing these two can help determine whether hearing loss is occurring within the middle ear which conducts sound from the ear canal to the inner ear (conductive hearing loss), or in the inner ear...