Electronic device and voiceprint authentication method

A voiceprint authentication method performed in an electronic device which uses a voiceprint for user authentication, comprising the steps of:

• registering a voiceprint;
• and
• performing user authentication after the step of registering a voiceprint, the step of registering a voiceprint including the steps of
• generating a first voiceprint from a first voice corresponding to a first character string,
• registering the first voiceprint,
• generating a second voiceprint from a second voice corresponding to a second character string longer than the first character string, and
• registering the second voiceprint, wherein the first and second voices are provided by a single person, and
• the step of performing user authentication including the steps of
• generating a third voiceprint from a third voice,
• making a first comparison between the first voiceprint and the third voiceprint,
• determining whether a first user authentication has been successful based on a result of the first comparison,
• generating a fourth voiceprint from a fourth voice uttered after the third voice when the first user authentication has failed, wherein the third and fourth voices are provided by a single person,
• making a second comparison between the second voiceprint and the fourth voiceprint, and
• determining whether a second user authentication has been successful based on a result of the second comparison, wherein
• determining whether the first user authentication has been successful comprises calculating a first similarity between the first voiceprint and the third voiceprint in the first comparison, to determine that the first user authentication has been successful when the first similarity is greater than a prescribed first threshold value, and to determine that the first user authentication has failed when the first similarity is smaller than the first threshold value, and
• determining whether the second user authentication has been successful comprises calculating a second similarity between the second voiceprint and the fourth voiceprint in the second comparison, to determine that the second user authentication has been successful when the second similarity is greater than a prescribed second threshold value, and to determine that the second user authentication has failed when the second similarity is smaller than the second threshold value, and
• wherein the second threshold value is smaller than the first threshold value.