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PurposeDistortion product otoacoustic emission (DPOAE) amplitude is sensitive to the primary tone level separation effective within the cochlea. Despite potential for middle ear sound transmission characteristics to affect this separation, no primary tone level optimization formula accounts for its influence. This study was conducted to determine if inclusion of ear- and frequency-specific immittance features improves primary tone level optimization formula performance beyond that achieved using a univariate,L2-based formula.MethodFor 30 adults with normal hearing, DPOAE, wideband absorbance, and 226-Hz tympanometry measures were completed. A mixed linear modeling technique, incorporating both primary tone and acoustic immittance features, was used to generate a multivariable formula for the middle ear–specific recommendation of primary tone level separations forf2= 1–6 kHz. The accuracy with whichL1OPT, or theL1observed to maximize DPOAE level for each givenL2, could be predicted using the multivariable formula was then compared with that of a traditional,L2-based univariate formula for each individual ear.ResultsUse of the multivariable formulaL1= 0.47L2+ 2.40A+f2param+ 38 [dB SPL] resulted in significantly more accurateL1OPTpredictions than did the univariate formulaL1= 0.49L2+ 41 [dB SPL]. Although average improvement was small, meaningful improvements were identified within individual ears, especially forf2= 1 and 6 kHz.ConclusionIncorporation of a wideband absorbance measure into a primary tone level optimization formula resulted in a minor average improvement inL1OPTprediction accuracy when compared with a traditional univariate optimization formula. Further research is needed to identify characteristics of ears that might disproportionately benefit from the additional measure.