(Supplementary note 13) A personal authentication program for causing a computer to execute: a process of calculating an acoustic property, from a first acoustic signal transmitted to a part of a head of a user and a second acoustic signal which is an acoustic signal after the first acoustic signal propagates through the part of the head; and a process of identifying the user, based on the acoustic property or a feature value extracted from the acoustic property and relating to the user.

(Supplementary note 14) The personal authentication program according to supplementary note 13, causing the computer to, in the user identification process, identify the user by comparing the acoustic property or feature value acquired from the second acoustic signal with an acoustic property or feature value stored in storage means for storing beforehand, for at least one person, an acoustic property at the time of propagation of an acoustic signal through a predetermined part of the head or a feature value extracted from the acoustic property.

(Supplementary note 15) A personalization system including service provision means for providing a service different for each person based on a user identification result by the personal authentication device according to any one of supplementary notes 1 to 10.

(Supplementary note 16) A content right management system including determination means for determining whether or not a user has a legitimate right to content subjected to management, based on a user identification result by the personal authentication device according to any one of supplementary notes 1 to 10.