Ear-canal geometries can vary significantly from human to human. The differences in geometry (length, width, etc.) can affect the resulting pressure at the eardrum. Headphones are often designed to match a target pressure-response curve at the drum reference point of some ear simulator. However, due to the individual differences the pressure response from an insert earbud at the eardrum of individual human ears can differ by several dB compared to the response of the simulator. In addition to ear canal geometry, the quality of the fit between the earbud tip and ear canal influences the pressure response at low frequencies.
In this work, we introduce an equalization method that uses measurements at a near-field microphone in the earbud tip to estimate the personalized transfer function from near-field microphone to the eardrum. Knowledge of this personalized transfer function allows for personalized equalization of the sound pressure at the eardrum. The presented method takes into account the personal ear canal geometry as well as the quality of the seal between earbud tip and ear canal.
We conducted a listening test to subjectively compare the personalized equalization algorithm against equalization using a mannequin-derived transfer function, and against the default voicing of the earbuds without equalization. The results show that the personalized equalization was favored on average with statistical significance.
(See document for exact affiliation information.)
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