Introduction: Acoustic reflectometry identifies the presence of middle ear fluid by measuring the difference between reflected and incident sound waves. We compared results using acoustic reflectometry with findings of middle ear fluid at the time of tympanostomy tube placement.

Methods: Children having tympanostomy tubes placed were eligible for the study. Acoustic reflectometry (EarCheck Pro, MDI Instruments, Woburn, MA) was performed immediately prior to surgery. Measurements of the eardrum's resonance curve were recorded and stratified into 5 groups based on the spectral gradient angle.

Results: Surgery was performed on 121 children; 201 ears were examined. Children were 63% male; mean age was 41.6 months. At surgery middle ear fluid was found in 107/201 ears (53%).

Spectral gradient angle and percent of children with fluid at surgery Table

Table 1 No caption available.
Full size table

Conclusion: Acoustic reflectometry provides information which helps to identify presence of middle ear fluid. Lower spectral gradient angles were associated with increased likelihood of presence of middle ear fluid. Data comparing this instrument with tympanometry, pneumatic otoscopy, otomicroscopy and audiology will also be presented.