A Study on the relationship between the geometrical shapes and the biometrical acoustic characteristics of human ear canal

Ear acoustic authentication is a new biometrics method and it utilizes the differences in acoustic characteristics of the ear canal between users. However, there have been few reports on the factors that cause differences in the acoustic characteristics. We investigate the relationship between ear canal shapes and acoustic characteristics in terms of user-to-user similarity. We used magnetic resonance imaging (MRI) to measure ear canal geometry. As a result, the correlation coefficient between shape similarity and acoustic characteristic similarity is higher than 0.7 and the coefficient of determination is higher than 0.5. This suggests that the difference in the shape of the ear canal is one of the important factors.