ABSTRACT To improve the accuracy of the sound image localization technique using bone conduction headphones and head‐related transfer functions, this paper proposes a preprocessing method using the difference of transfer characteristics between from the entrance of ear canal to cochlea and from transducer to cochlea. The estimation of the differential characteristic is performed using Distortion Product OtoAcoustic Emission (DPOAE) and the preprocessing is realized using finite impulse response (FIR) digital filters. In subjective experiments on sound image localization, it was confirmed that the proposed method improves the localization accuracy compared to the case without preprocessing.