The ear canal geometries of individuals are very different, resulting in significant variations in SPL at the drum reference point (DRP). Knowledge of the personalized transfer function from a near-field microphone (NFM) in the earbud speaker tip to DRP allows personalized equalization (P.EQ). A method to perceptually compensate for loudness perception within the evaluation of different personalized equalization filters for earbuds has been developed. The method includes: measurements at NFM to estimate the personalized transfer function from the NFM point to DRP, calibration of the NFM microphone, the acquisition of the transfer function from the earbuds speaker terminals to NFM, and the estimation of perceptual loudness in phones at DRP, when applying the different equalization filters. The loudness estimation was computed using the Moore-Glasberg method as implemented in ISO 532-2. The difference to DRP estimation was recursively adjusted using pink noise until the delta was within 0.1 dB. The corresponding gains were applied to the different conditions to be evaluated. A listening test was performed to evaluate three conditions using the described method for loudness compensation.
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