An Analysis of 226 Hz Acoustic Reflex in Normal Neonates

Objective To study the tympanogram and acoustic-reflex of normal neonatesand to discuss the clinical application of acoustic immitance.Methods The acoustic reflection check(screening type) and tympanic pressure test were performed in 842 neonates(1684 ears) passing hearing screening using transiently evoked otoacoustic emission(TEOAE),and the results of the tympanometry and acoustic-reflex tests were analyzed.Results The 226 Hz single admittance(Y) tympanograms included bimodal,unimodal and flat types,accounted for 36.52%,57.78% and 5.7%,respectively;the 90% reference range of the neonatal external canal volume was 0.3-0.8 ml;the 90% reference range of thestatic compliance value was about 0.2-0.9 ml;the 90% reference range of tympanometric peak pressure(TPP) was-17.25 to 100.00 daPa;tympanometric width was 50-180 daPa.At 226 Hz-probe and 1000 Hz stimulating sound,the positive rate of ipsilateral acoustic reflex was 21.62% of all ears.Conclusion The neonatal ear canal volume,peak compensated static acoustic admittance,tympanometric peak pressure and tympanometric width can be applied in the neonatal hearing screening.226 Hz-acoustic reflex cannot appear in a large part of the newborns.