A curve showing the transmission of energy through the middle ear at various air pressures in the external auditory canal (EAC). It gives a crude but objective assessment of conductive hearing loss, and various middle ear disorders yield distinctive patterns of tympanogram:

  • tympanogram A: a symmetrical triangular graph with its peak at zero pressure level represents normal middle ear function
  • tympanogram B: a flat line on the graph represents the middle ear space filled with fluid, restricting movement of the tympanic membrane under the externally applied pressure
  • tympanogram C: this is found when there is a reduction of middle ear pressure relative to the air pressure in the EAC, which causes inward retraction of the tympanic membrane; the graph shows the shift of the tympanographic peak into the negative value range, but it is of a normal shape.