Audiometry consists of tests of function of the hearing mechanism. This includes tests of mechanical sound transmission (middle ear function), neural sound transmission (cochlear function), and speech discrimination ability (central integration). A complete evaluation of a patient's hearing must be done by trained personnel using instruments designed specifically for this purpose.Pure tones (single frequencies) are used to test air and bone conduction. These and speech testing are done with an audiometer. The audiometer is an electric instrument consisting of a pure tone generator, a bone conduction oscillator for measuring cochlear function, an attenuator for varying loudness, a microphone for speech testing, and earphones for air conduction testing.