Comparison of High Frequency and Low Frequency Tympanometry Findings in Normal Neonates

Tympanometry is one of the most important audiological tests for the assessment of neonatal hearing screening programs. This test is usually done using a 226 Hertz probe tone; however, in infants less than 6 months of age, using this probe tone frequency is not reliable due to the different characteristics of the middle ear compared to adults. The purpose of this study was to assess the obtained tympanometric data in neonates 1 to 14 days with normal hearing using 226, 678, 800 and 1000 Hertz frequency probes tones.
In this cross-sectional study, 30 neonates aged 1 to 14 days who were diagnosed as normal in hearing aspect with using otoacoustic emissions test, were assessed by tympanometry. Tympanometric tests were performed using 226, 678, 800 and 1000 Hertz frequency probe tones for both ears. For data analysis, the T-paired method has been used.
With using 226 Hertz frequency probe tone, incidence of unusual double peak tympanograms was observed in 65% of cases, which with increasing frequency of the probe tone, this percentage was decreased. There was also a statistically significant difference between the static admittance peak compensated in two 226 and 1000 Hertz frequency probes tones.
In neonates with normal hearing and without any risk factors for hearing loss, the 1000-Hertz Tympanogram shows a better middle ear status than the 226-Hertz tympanogram.