[Investigation of tympanogram in newborns with 226 hz and 1000 hz probe tones]

Abstract

Objective: This study aims at investigating tympanogram in newborns who passed hearing screening using 226 and 1 000 Hz probe tones in order to interpret the test results correctly and find out its clinical value in audiological evaluation and diagnosis in this population.

Method: Tympanogram was conducted using 226 and 1000 Hz probe tones in 206 newborns between 2 and 7 days of age (3.92 +/- 1.24) in both ears that passed the DPOAE screening and without any of the high risk register (HRR) factors associated with hearing loss according to the Joint Committee on Infant Hearing in 2007.

Result: The tympanogram results tested in 408 ear were as following: the percentage of single-peaked, double-peaked, and none-peaked tympanograms using 226 Hz were 52.20% (213 ears), 47.55% (194 ears) and 0.25% (1 ear) respectively. The percentage of single-peaked and other morphological type tympanograms using 1000 Hz were 94.85%(387 ears) and 5.15% (21 ears) respectively. The parameters of 1000 Hz single-peaked tympanogram in this study were as following: the average tympanometric peak pressure was 33.24 +/- 44.37 dapa, the average peak compensated static acoustic admittance was 0.52 +/- 0.25 mmho, the average tympanometric width for right and left ears were 121.38 +/- 28.79 and 108.63 +/- 26.00 dapa respectively with a statistically significant difference between them (P < 0.01). The average volume of ear canal (Vec, using 226 Hz probe tone) at boys and girls were 0.44 +/- 0.10 and 0.43 +/- 0.08 ml respectively with a statistically significant difference between them (P < 0.05).

Conclusion: The morphology of tympanogram using a 226 Hz probe tone in newborns usually includes two main types: single-peaked and double-peaked, while it is primarily the single-peaked tympanogram while using a 1000 Hz probe tone. It is more appropriate to use a 1000 Hz probe tone than 226 Hz when testing newborns' tympanogram. The parameters obtained in this study using 1000 Hz and 226 Hz could be tried and applied to interpret clinical tympanogram test results and evaluate middle ear function. However, more studies with bigger sample size are necessary in this field.