Predicting Behavioral Thresholds From DPOAE I/O Functions

Predicting Behavioral Thresholds From DPOAE I/O Functions
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Michael P. Gorga, Stephen T. Neely, Patricia A. Dorn, and Brenda M.Hoover
09 January 2014

Summarized from JASA 113, pages 3275-3284

Level: Advanced

Numbers of Slides: 35


Recently, Boege and Janssen (J. Acoust. Soc. Am. 111, 1810 -1818, 2002) fit linear equations to distortion product otoacoustic emission DPOAE input/output I/O functions after the DPOAE level (in dB SPL) was converted into pressure (uPa). Significant correlations were observed between these DPOAE thresholds and audiometric thresholds. The present study extends their work by (1) evaluating the effect of frequency,(2) determining the behavioral thresholds in those conditions that did not meet inclusion criteria, and (3) including a wider range of stimulus levels. DPOAE I/O functions were measured in as many as 278 ears of subjects with normal and impaired hearing. Nine f2frequencies (500 to 8000 Hz in1/2-octave steps) were used, L2 ranged from 10 to 85 dB SPL(-5dB steps), and L1was set according to the equation L1 = 0.4L2 +39 dB (Kummer et al., J. Acoust. Soc. Am. 103, 3431-3444, 1998)# for L2l evels up to 65 dB SPL, beyond which L1 = L2. For the same conditions as those used by Boege and Janssen, we observed a frequency effect such that correlations were higher for mid-frequency threshold comparisons. In addition, a larger proportion of conditions not meeting inclusion criteria at mid and high frequencies had hearing losses exceeding 30 dB HL, compared to lower frequencies. These results suggest that DPOAE I/O functions can be used to predict audiometric thresholds with greater accuracy at mid and high frequencies, but only when certain inclusion criteria are met. When the SNR inclusion criterion is not met, the expected amount of hearing loss increases. Increasing the range of input levels from 20-65 dB SPL to 10-85 dB SPL increased the number of functions meeting inclusion criteria and increased the overall correlation between DPOAE and behavioral thresholds. 

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