Hearing evaluations and screenings are performed by the audiologist after obtaining a thorough case history. The hearing evaluation typically includes pure-tone testing, speech recognition testing, and middle ear testing. Pure-tone testing determines the smallest tone that a person can hear across frequencies from lowest to highest loudness level. Tones are presented to patients in each ear through headphones, and patients usually press a button indicating that they have heard the tone. Speech recognition testing determines the softest speech that a person can hear half of the time. Once a speech recognition threshold (SRT) has been confirmed, the audiologist will find the patient’s most comfortable loudness level to determine the word recognition score (WRS), or the ability to correctly repeat words. Speech recognition testing helps to confirm pure-tone findings. Middle ear testing includes tympanometry, which detects fluid, eardrum perforation, or wax. During tympanometry, the ear drum moves back and forth as a result of pressure created by a tube inserted into the ear canal. Information from this test is recorded on a tympanogram, which shows the characteristics of eardrum mobility. Other middle ear tests include acoustic reflex measures and static acoustic impedance. Additional tests for hearing evaluations include auditory brainstem response and otoacoustic emissions.