Optimal stimulus level conditions for measurements of distortion product otoacoustic emissions.

Objective: Distortion product otoacoustic emission (DPOAE) is a tool for an objective examination of the cochlea function. While the clinical application of DPOEA test is in progress, the measurements vary depending on the stimulus conditions. We aimed to determine the most appropriate stimulus level in the clinical application of DPOAE test. Methods: Ninety-seven normal hearing ears and 80 hearing-impaired ears (total 177) were subjected to this study. Two levels of stimulations (L1 and L2) were applied as follows: L1=L2=70 dB; L1=L2=60 dB and L1=60/L2=50 dB, and DP level was measured at each stimulation, and compared with hearing level. Results: DP level was highest at L1=L2=70 dB. Normal hearing ears and hearing-impaired ears were well differentiated at L1=L2=60 dB. Conclusion: In clinical application of DPOAE test, DP levels should be measured at the stimulus level most appropriate for the purposes.