Feasibility of 1000 Hz tympanometry in infants

OBJECTIVES: Universal newborn hearing screening (UNHS) has significantly reduced the age of children undergoing audiological examinations. Middle ear function is usually evaluated with tympanometry using a probe tone of 226 Hz, although higher frequencies are recommended in infants. The aim of this study was to compare the feasibility of 226 and 1000 Hz tympanometry for different trace classification systems in relation to age, risk factors for hearing loss and ear canal volume. METHODS: Data from 577 infants (915 ears) <1 year were analyzed. Tympanograms were classified according to the classification systems of Jerger, Marchant et al. and Kei et al. and correlated with ear microscopy as the gold standard. Test quality parameters of tympanometry with probe tones of 226 and 1000 Hz were compared in four different age groups. RESULTS: The trace classification following Kei et al. presented the best correlation to ear microscopy and reduced the number of unclassified tympanograms. The use of probe tones of 226 Hz in infants below the age of nine months showed a poor level of sensitivity. CONCLUSIONS: We recommend the use of a 1000 Hz probe tone in infants at least up to the age of nine months. In this age group, 226 Hz tympanometry is inappropriate. In children with craniofacial abnormalities and smaller ear canal volumes, 1000 Hz tympanometry could be taken into consideration, even for older children. High-frequency tympanograms should be evaluated according to the classification system of Kei et al., which differentiates between peaked (normal) and flat (abnormal) curves.