effects of age, sex, ears, and weight on high frequency tympanometry 1000 hz characteristics in neonates with normal transient evoked otoacoustic emission

Background and aim: middle ear of neonates is mass-dominant. therefore, by increasing the frequency of probe tone from 226 hz to 1000 hz, middle ear abnormalities can be detected better. this study aimed to evaluate the effect of age, sex, ear and weight on the characteristics of 1000 hz tympanometry in neonates. methods: a total of 255 neonates (136 boys and 119 girls) aged from 1 to 90 days, with normal transient evoked otoacoustic emissionat least in one ear were studied. compensated static admittance at middle ear pressure (ypp) and admittance at pressure of +200 dapa (y200) were measured with 1000 hz tympanometry. results: mean (sd) ypp and y200 values were 0.97 (0.48) and 2.07 (0.46) mmho in the right ears and 0.98 (0.53) and 2.05 (0.48) mmho in the left ears, respectively. in both ears, gender had no significant effect on compensated ypp, but y200 values were significantly different between girls and boys (p<0.05). ear did not affect the ypp and y200 values. there was also a linear relationship between age and weight with compensated ypp and y200 values, so that compensated ypp and y200 values increased with higher weight and age. conclusion: age and weight by affecting the physical and impedance characteristics of ear canal and tympanic membrane, can also affect the characteristics of the high frequency tympanometry. lack of gender effects on compensated ypp and its effect on y200 can be attributed to the difference in compliance between tympanic membrane and ear canal in boys and girls.