Why use High Frequency Tympanometry?
A. For some years it has been recognised that conventional low-frequency probe tone tympanometry is inappropriate for infants below about 7 months of age, because of the poor sensitivity (ie, high false negatives) of conventional tympanometry to middle ear disease in young infants. The main limitation of low-frequency probe tone tympanometry appears to be the presence of Type A tympanograms based on the Jerger/Liden classification (Jerger, 1970; Liden, 1969) despite the presence of middle ear effusion diagnosed otoscopically or surgically. More recently Keefe and Levi (1996) noted that some infants with flat 226 Hz tympanograms have middle ear energy reflectance in the normal range at higher frequencies, which suggests also that false positives as well as false negatives occur when using low-frequency probe tone tympanometry in infants.
