An audiogram is a graph that shows the audible threshold for standardized frequencies as measured by an audiometer. The Y axis represents intensity measured in decibels and the X axis represents frequency measured in Hertz It also measures the pressure in the space behind the eardrum that contains those bones. For tympanometry, a soft rubbery tip is inserted in the ear and the pressure in the ear canal is changed, resulting in a feeling like going up in an airplane.