Characteristics of Wideband Acoustic Immittance in Patients with Middle-Ear Dysfunction

Abstract

Background: Wideband acoustic immittance (WAI) measurements are a relatively new class of aural acoustic tests that have shown promise as useful tools for evaluating middle-ear status. A growing body of work has described WAI for infants, children, and adults with normal middle-ear function, but a relatively limited number of studies have investigated the influence of specific middle-ear disorders on WAI. Although emerging WAI research data show promising results, additional measurements from ears of patients with a variety of middle-ear disorders are needed. Purpose: The aims of the present study were to (1) obtain WAI data from patients with a variety of middle-ear conditions, (2) examine relationships between WAI data relative to standard audiometric tests, and (3) identify patterns or profiles in WAI data within and among patients with different middle-ear conditions. Research Design: A descriptive study. Study Sample: Participants included 30 children and two adults with a variety of middle-ear disorders who were recruited from clinical audiology settings. Data Collection/Analysis: Experimental ambient and tympanometric WAI data were gathered along with standard audiometric test data as part of clinical audiology appointments. Single-subject and small-group data sets for ears of patients with suspected otitis media with effusion (sOME), pressure equalization (PE) tubes, negative tympanometric peak pressure (TPP), tympanoplasty, and cerumen impaction were obtained. Qualitative analysis and descriptive statistics (means and percentiles) were used to characterize the data. Results: Group mean absorbance for ears in the sOME group was reduced across the majority of frequencies; absorbance for ears with negative TPP was also reduced, although to a lesser degree. Absorbance patterns for ears with PE tubes show even greater differences because of the effects of the tube and open middle-ear cavity. WAI from ears with a tympanoplasty and cerumen impaction was suggestive of middle-ear dysfunction in the presence of normal single-frequency tympanometry. Percentile (5th, 50th, and 95th) plots for absorbance and other WAI quantities of admittance level, admittance phase, and equivalent ear-canal volume calculated for the sOME, negative TPP, and PE tube groups showed distinctive profiles that might be useful for discrimination of different middle-ear pathologies. Quantities from wideband tympanometry, including 250- and 1000-Hz single-frequency admittance tympanometric data were also derived. Conclusions: WAI measurements for some middle-ear conditions were consistent with patterns and profiles previously reported in the literature. WAI profiles for other middle-ear conditions, which had not been previously reported in the literature, were presented. Relationships between WAI data and results of standard audiometric tests were generally consistent with expectations. However, in some cases, WAI measurements were suggestive of middle-ear dysfunction despite normal 226-Hz admittance tympanometric findings.