The middle ear, a part of the hearing organ, transfers sounds into the inner ear. Tympanometry is a clinical procedure that assesses middle ear function, in which the acoustic admittance is measured with the ear canal air pressure systematically varied. In recent years, tympanometry using 1000-Hz probe tone was suggested to be more reliable in testing infants. Absent research on procedural variables has resulted in difficulties in establishing clinical norms. This study provided the first set of data in 23 adults showing that air pressure change rate significantly alters 1000-Hz tympanograms. This effect generally depends on admittance components measured and tympanogram pattern.