Wideband energy reflectance measurements: normative study and effects of negative and compensated middle ear pressures

Abstract

Conventional clinical procedures for middle ear assessment have been used for several decades but have shown limitations. Application of a new technology, wideband energy reflectance (ER), has shown great potential. The ER measurement determines the proportion of acoustic energy reflected by the middle ear, across a broad frequency range. Negative middle ear pressure (MEP) is a highly prevalent, and mostly transient, form of middle ear dysfunction which effects ER measurement. Goals of the present study were to examine various factors relating to the ER test: (1) test-retest reliability, (2) the effects of pressure manipulations, (3) the effects of negative MEP, and (4) the effectiveness of a corresponding compensation procedure. Data were collected in 48 adults and analyzed across the frequency range from 0.223 to 8 kHz. Measurements were conducted using both ambient and dynamic pressure methods, under three conditions: normal MEP, negative MEP, and compensated negative MEP. Correlation between immediately repeated tests were strong for all frequencies. The sweeping pressure procedure caused ER reduction for a few frequencies but differences were small. Thirty-five subjects were able to produce a negative MEP ranging from -40 to -220 daPa. Negative MEP increased ER at low- and mid-frequencies while decreasing ER at high-frequencies. Magnitude of changes and frequency at which maximum change occurred increased when MEP became more negative. Compensated negative MEP reduced ER at low- and mid-frequencies but increased ER at high- frequencies. The present study demonstrated that negative MEP altered ER in a frequency-specific pattern. The compensation procedure eliminated the effects of negative MEP. Immediate test-retest reliability of the ambient ER test was excellent. Both probe reinsertion and manipulation of the ear canal and middle ear pressure produced minimal effects.