Acoustic stapedial reflex in normal adults: Biological behavior and determination of threshold levels

Objective: To record acoustic reflex thresholds for admittance (Y) and its components, susceptance (B) and conductance (G) in healthy subjects and to establish normative data. StudyDesign: Acoustic reflex threshold was determined in 100 healthy persons, divided into 5 age groups of 20 persons each (20-29, 30-39, 40-49, 50-59 and 60-69 years old). Detection was performed for Y, B, and G at 226-, 678- and 1,000-Hz probe tones, using 500-, 1,000-, 2,000- and 4,000-Hz stimuli. Results: Statistically significant differences in acoustic reflex thresholds were revealed between different components, stimuli and tones. The lowest threshold level was recorded for Y at 226 Hz using stimulus 1,000 Hz. Four percent missing values were observed at 226 Hz. Subjects belonging to different age groups had different reflex thresholds. Conclusion: Inclusion of acoustic reflex detection for B and G offers more detailed information about the middle ear status compared with Y alone, and appears to be sensitive in detecting subtle diseases.