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Longitudinal investigation of middle ear function using multi-frequency, multi-component tympanometry from birth to six months of age Cai, Anika

Abstract

Objectives: The specific goals of this study were: 1) To understand the mechano-acoustical properties of the normal ear canal and middle ear and its maturation as a function of age using conventional and high frequency tympanometry 2) to establish tympanometric guidelines and normative data of the normal ear canal and middle ear in infants birth to 6 months of age. Design: Thirty-one normal hearing newborns were tested longitudinally in 1-month intervals up to 6 months of age for a total of 6 visits. Tympanograms were recorded and the distributions of patterns were analyzed using the Vanhuyse model at 226 Hz, 678 Hz, and 1000 Hz. Additionally, tympanometric recordings of admittance (Ya), susceptance (Ba), and conductance (Ga) were analyzed at 226 Hz and 1000 Hz probe tones. Lastly, the variation of compensated susceptance and conductance were recorded at extended frequencies from 250-2000 Hz in 50 Hz intervals for 16 infants. Results: Results showed that 1000 Hz tympanograms were the simplest to quantify as most recordings were single-peaked. 226 Hz and 678 Hz recordings were often multi-peaked. Both positive and negative admittance and susceptance tail values increased with age for 226 Hz and 1000 Hz. However, tail values at 1000 Hz increased faster than for 226 Hz. Negative tail values were smaller compared to positive tail values which resulted in smaller compensated admittance values for the positive tails compared to negative tails across all 6 visits. Admittance magnitude decreased with age at 226 Hz as susceptance increased and conductance decreased. However, at 1000 Hz, admittance magnitude increased as susceptance remained relatively constant and conductance increase. Conclusion: Results suggest that the infant middle ear and ear canal develop towards compliance with age although is not yet a purely acoustically compliant system by 6 months of age, particularly at high frequencies. An increase in volume in the middle ear cavity, reduction of middle ear debris, and overall decrease in resistive elements may be contributing to these changes. Significant differences were observed between each visit and warrant the use of age-specific norms when applying tympanometric data to infants below 6 months of age.

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