Immittance Findings in Infants Using Different Probe Tone Frequencies

Abstract

The study aimed at providing tympanometric measures such as tympanometric peak pressure (TPP), Peak compensated static acoustic admittance compensated with +ve and –ve tail, (Y+400 & Y-600,), ear canal volume (ECV) using 226 Hz, 678 Hz and 1000 Hz probe tone frequencies and ipsilateral acoustic reflex thresholds (ARTs) at 500 Hz, 2000 Hz and 4000 Hz using 226 Hz and 1000 Hz probe tones in infants of 2 – 12 months age range. Seventy normal hearing infants who were divided into 4 subgroups with 25 infants in 2 – 4 months age group, 15 infants each in the age groups of 4 – 6 months, 6 – 8 months and 8 – 12 months respectively participated in the study. The results are analyzed qualitatively and quantitatively. The qualitative analysis for tympanograms showed that % of ears with single peaked tympanogram increases and double peaked tympanogram decreases with age, for 226 Hz and 678 Hz probe tones. On the other hand, for 1000 Hz probe tone, the % of ears with single peaked tympanogram decreases and % of ears with double peaked tympanogram increases with age. The ARTs at 500 Hz and 2000 Hz were present in all infants. But ARTs were present in 83.6% and 86.4% of ears when 226 Hz and 1000 Hz probe tones were used. Quantitative analysis was done using appropriate statistical tools which showed significant effect of age and probe tone frequency on tympanometric and ART measures.