Tympanometry is a test that is used to determine if there is abnormality in the middle ear system. This system includes the eardrum (tympanic membrane), the ossicles (three tiny middle ear bones), and their mechanical ability to conduct sound into the cochlea (end organ of hearing). A probe, placed at the entrance to the outer ear canal, generates tones and varying degrees of air pressure that automatically registers middle ear mobility and function on audiometric equipment. This is one of the three minimal procedures used in assessment of all who require hearing testing and can be used in conjunction with OAEs to help rule out auditory neuropathy. Since middle ear disorders (fluid behind the ear drum, middle ear infection, abnormal movement of the ossicles, etc.) are more common in babies and children, this test is useful and does not require the child (or adult) to volunteer a response.