Personal authentication device based on echo sounds, personal authentication method, and recording medium

A personal authentication method comprising:

• outputting a first acoustic signal to earphone, the first acoustic signal being signal for sound is transmitted from the earphone;
• receiving a second acoustic signal from the earphone, the second acoustic signal being signal based on echo sound being the sound echoed in an ear of the user;
• calculating a first feature amount related to the user based on the second acoustic signal;
• collating the first feature amount with a second feature amount registered with one or more memories;
• and
• outputting a third acoustic signal being different from the first acoustic signal to the earphone based on a collation result, wherein
• the personal authentication method comprises:
• recognizing the user as user authorized to use the earphone based on the collation result;
• providing a service to the user when the collation result indicate coincidence;
• when the collation result does not indicate the coincidence, providing of the service is stopped and the second feature amount registered within the one or more memories is deleted from the one or more memories;
• and
• detecting whether a specified time has passed,
• when the collation result indicate coincidence and it is detected that the specified time has passed, the providing of the service to the user is stopped.

A non-transitory computer readable recording medium stored with a personal authentication program causing a computer to perform:

• outputting a first acoustic signal to earphone, the first acoustic signal being signal for sound is transmitted from the earphone;
• receiving a second acoustic signal from the earphone, the second acoustic signal being signal based on echo sound being the sound echoed in an ear of the user;
• calculating a first feature amount related to the user based on the second acoustic signal;
• collating the first feature amount with a second feature amount registered with one or more memories;
• and
• outputting a third acoustic signal being different from the first acoustic signal to the earphone based on a collation result, wherein
• the personal authentication program causes the computer to perform:
• recognizing the user as user authorized to use the earphone based on the collation result;
• providing a service to the user when the collation result indicate coincidence;
• when the collation result does not indicate the coincidence, providing of the service is stopped and the second feature amount registered within the one or more memories is deleted from the one or more memories;
• and
• detecting whether a specified time has passed,
• when the collation result indicate coincidence and it is detected that the specified time has passed, the providing of the service to the user is stopped.