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Do “Optimal” Conditions Improve Distortion Product Otoacoustic Emission Test Performance?

Kirby, Benjamin J.1,2; Kopun, Judy G.1; Tan, Hongyang1; Neely, Stephen T.1; Gorga, Michael P.1

doi: 10.1097/AUD.0b013e3181fa5da2
Research Articles
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Objectives: To determine whether an “optimal” distortion product otoacoustic emission (DPOAE) protocol that (1) used optimal stimulus levels and primary-frequency ratios for each f2, (2) simultaneously measured 2f2f1 and 2f1f2 distortion products, (3) controlled source contribution, (4) implemented improved calibration techniques, (5) accounted for the influence of middle ear reflectance, and (6) applied multivariate analyses to DPOAE data results in improved accuracy in differentiating between normal-hearing and hearing-impaired ears, compared with a standard clinical protocol.

Design: Data were collected for f2 frequencies ranging from 0.75 to 8 kHz in 28 normal-hearing and 78 hearing-impaired subjects. The protocol included a control condition incorporating standard stimulus levels and primary-frequency ratios calibrated with a standard SPL method and three experimental conditions using optimized stimuli calibrated with an alternative forward pressure level method. The experimental conditions differed with respect to the level of the reflection-source suppressor tone and included conditions referred to as the null suppressor (i.e., no suppressor tone presented), low-level suppressor (i.e., suppressor tone presented at 58 dB SPL), and high-level suppressor (i.e., suppressor tone presented at 68 dB SPL) conditions. The area under receiver operating characteristic (AROC) curves and sensitivities for fixed specificities (and vice versa) were estimated to evaluate test performance in each condition.

Results: AROC analyses indicated (1) improved test performance in all conditions using multivariate analyses, (2) improved performance in the null suppressor and low suppressor experimental conditions compared with the control condition, and (3) poorer performance below 4 kHz with the high-level suppressor. As expected from AROC, sensitivities for fixed specificities and specificities for fixed sensitivities were highest for the null suppressor and low suppressor conditions and lowest for standard clinical procedures. The influence of 2f2f1 and reflectance on test performance were negligible.

Conclusions: Predictions of auditory status based on DPOAE measurements in clinical protocols may be improved by the inclusion of (1) optimized stimuli, (2) alternative calibration techniques, (3) low-level suppressors, and (4) multivariate analyses.

An “optimal” distortion product otoacoustic emission (DPOAE) protocol that (1) used optimal stimulus levels and primary-frequency ratios for each f2, (2) simultaneously measured 2f2f1 and 2f1f2 distortion products, (3) controlled source contribution, (4) implemented improved calibration techniques, (5) accounted for the influence of middle ear reflectance, and (6) applied multivariate analyses to DPOAE data was compared with a standard clinical protocol for the purpose of differentiating normal-hearing and hearing-impaired ears. Predictions of auditory status based on DPOAE measurements in clinical protocols were improved by the inclusion of (1) optimized stimuli, (2) alternative calibration techniques, and (3) multivariate analyses.

1Boys Town National Research Hospital, Omaha, Nebraska; and 2Department of Communication Sciences and Disorders, The University of Iowa, Iowa City, Iowa.

This work was supported by grants T35 DC8757, R01 DC2251, R01 DC6350, and P30 DC4662 from National Institutes of Health.

Address for correspondence: Michael P. Gorga, Boys Town National Research Hospital, 555 North 30th Street, Omaha, NE 68131. E-mail: michael.gorga@boystown.org.

Received April 14, 2010; accepted August 27, 2010.

© 2011 Lippincott Williams & Wilkins, Inc.