Personal authentication device, personal authentication method, and personal authentication program using acoustic signal propagation

1. A personal authentication device comprising:

an acoustic signal transmission unit which transmits a first acoustic signal to a part of a head of a user;

an acoustic signal observation unit which observes a second acoustic signal which is an acoustic signal after the first acoustic signal propagates through the part of the head;

an acoustic property calculation unit implemented at least by a hardware including a processor and which calculates an acoustic property from the first acoustic signal and the second acoustic signal; and

a user identification unit implemented at least by the hardware and which identifies the user, based on the acoustic property or a feature value extracted from the acoustic property and relating to the user,

wherein the acoustic signal transmission unit is further configured to transmit a transmission acoustic signal used for removing ambient noise and/or a device property not dependent on the positional difference in the head to a right ear canal and a left ear canal of the user simultaneously, or pinnae of the user,

the device further comprising a removal unit implemented at least by the hardware and which removes the ambient noise and/or the device property from the second acoustic signal, by performing a calculation using at least two acoustic signals, based on the transmission acoustic signal, observed at two locations of the head.

2. The personal authentication device according to claim 1 , comprising

a storage unit which stores beforehand, for at least one person, an acoustic property at a time of propagation of an acoustic signal through a predetermined part of a head of the person or a feature value extracted from the acoustic property,

wherein the user identification unit identifies the user, by comparing the acoustic property calculated from the second acoustic signal with the acoustic property stored in the storage unit or comparing the feature value extracted from the acoustic property calculated from the second acoustic signal with the feature value stored in the storage unit.

3. The personal authentication device according to claim 1 , wherein the acoustic signal transmission unit is realized by an earphone, a headphone, or a receiver portion of a telephone, and

wherein the acoustic signal observation unit is realized by a microphone mounted on the earphone, the headphone, or the receiver portion of the telephone.

4. The personal authentication device according to claim 1 , wherein

the removal unit removes the ambient noise and/or the device property from the second acoustic signal, based on acoustic signals observed from a plurality of persons.

5. The personal authentication device according to claim 1 , wherein the acoustic signal transmission unit transmits an acoustic signal for bone conduction, as the first acoustic signal, and

the acoustic signal observation unit observes an acoustic signal after the first acoustic signal propagates through the part of the head by bone conduction, as the second acoustic signal.

6. The personal authentication device according to claim 1 , comprising

a noise estimation unit implemented at least by the hardware and which estimates a noise signal, based on an acoustic signal observed by the acoustic signal observation unit,

wherein the acoustic signal transmission unit transmits an acoustic signal of a frequency band different from a frequency band of the noise signal estimated by the noise estimation unit, as the first acoustic signal from next time.

7. The personal authentication device according to claim 1 , wherein the acoustic signal transmission unit changes the first acoustic signal regularly or irregularly.

8. The personal authentication device according to claim 1 , wherein

the acoustic signal transmission unit transmits acoustic signals a plurality of times; and

the removal unit averages two or more observed acoustic signals and removes the ambient noise and/or the device property from the second acoustic signal using an average value of the observed acoustic signals.

9. A personal authentication method comprising:

transmitting a first acoustic signal to a part of a head of a user;

observing a second acoustic signal which is an acoustic signal after the first acoustic signal propagates through the part of the head;

calculating by an information-processing device, an acoustic property from the first acoustic signal and the second acoustic signal;

identifying the user, by the information-processing device, based on the acoustic property or a feature value extracted from the acoustic property and relating to the user;

transmitting a transmission acoustic signal used for removing ambient noise and/or a device property not dependent on the positional difference in the head to a right ear canal and a left ear canal of the user, or pinnae of the user simultaneously; and

removing the ambient noise and/or the device property from the second acoustic signal, on the basis of at least two acoustic signals, based on the transmission acoustic signal, observed at two locations of the head.

10. The personal authentication method according to claim 9 , wherein

transmitting acoustic signals a plurality of times; and

averaging two or more observed acoustic signals and removing the ambient noise and/or the device property from the second acoustic signal using an average value of the observed acoustic signals.

11. A non-transitory computer readable recording medium in which a personal authentication program is recorded, the 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;

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;

a process of transmitting a transmission acoustic signal used for removing ambient noise and/or a device property not dependent on the positional difference in the head to a right ear canal and a left ear canal of the user, or pinnae of the user simultaneously; and

a process of removing the ambient noise and/or the device property from the second acoustic signal, on the basis of at least two acoustic signals, based on the transmission acoustic signal, observed at two locations of the head.