Correlation Between Pure Tone Hearing Thresholds and Distortion-Product Emission Levels

Abstract

It was recently revealed that in hearing loss of cochlear origin, the distortion-product otoacoustic emission (DPOAE) level plot against primary frequency reflects hearing threshold pattern very well. One would naturally expect that the test might provide objective data to estimate hearing thresholds. This possibility was tested by analyzing correlation between the pure tone audiometry thresholds and the DPOAE levels at 2f₁-f₂, in various degrees of patients with sensorineural hearing loss. Very good linear correlation was found between the pure tone thresholds and averaged DPOAE levels in the patients with mild to medium sensorineural hearing loss (<50dB). The correlation coefficient was especially high when the f₂ frequency was adjusted to the test frequency of the pure tone audiometry. However, the DPOAE level variances were so large that it was difficult to predict hearing thresholds of patients from DPOAE levels measured in their ears.
These rusults indicated that the DPOAE level measurement certainly leads to objective quantification of some aspects of cochlear function, but it is dangerous to estimate the hearing threshold values solely from this test.