Correction Factors and Predicting Hearing Loss from ABR
McCreery et al (2015) report that results from auditory brainstem response (ABR) of 309 ears (from 177 children) with respect to how the degree of hearing loss impacts the prediction of behavioral thresholds. Historically, it has been shown that as hearing loss increases, ABR thresholds increase, too. However, the previously established relationships have been imperfect. The authors proposed "a correction factor based on the linear relationship between the differences in ABR and behavioral thresholds as a function of ABR threshold resulted in more accurately predicted behavioral thresholds than other correction factors in clinical use."
That is, one of the objectives of their study was to develop and assess a protocol in which the magnitude of the applied correction factor depends on the degree of (estimated) hearing loss, predicted by the ABR. Therefore, linear regressions (LR) were used. Standardized regression coefficients at each frequency (500, 1000, 2000, and 4000 Hz) suggested the correspondence between ABR and behavioral thresholds decreased approximately 1 dB for every 3 dB increase in ABR threshold.
The authors report three conclusions can be drawn. First, estimation of behavioral thresholds can be readily accomplished via ABR. Second, differences between ABR and behavioral thresholds vary with respect to degree of hearing loss (ABR typically underestimates hearing loss for people with moderate or greater hearing loss). Third, frequency-specific correction factors based on the linear relationship (described earlier as "the correspondence between ABR and behavioral thresholds decreased approximately 1 dB for every 3 dB increase in ABR threshold") provided more accurate behavioral threshold predictions across all four test frequencies.
From Table 4 (page 315), the following correction factors (in dB) are offered. The chart below indicates the number of dB to be subtracted from the ABR threshold to predict behavioral thresholds.
|0||2px0 dB nHL||40 dB nHL||60 dB nHL||80 dB nHL|
For More Information, References, and Recommendations
McCreery RW, Kaminski J, Beauchaine K, Lenzen N, Simms K, Gorga MP. (2015) The Impact of Degree of Hearing Loss on Auditory Brainstem Response Predictions of Behavioral Thresholds. Ear & Hearing 36(3)309-319.