Authentication apparatus, authentication method, and recording medium

An authentication apparatus comprising:

• at least one memory configured to store instructions;
• and
• at least one processor configured to execute the instructions to:
• calculate, from an air conduction sound signal indicating an air conduction sound of a voice of a target person and a bone conduction sound signal indicating a bone conduction sound of the voice of the target person, an air conduction feature quantity that is a feature quantity of the air conduction sound signal and a bone conduction feature quantity that is a feature quantity of the bone conduction sound signal, and that calculates a target feature quantity that is a feature quantity of the voice of the target person by combining the air conduction feature quantity and the bone conduction feature quantity;
• and
• authenticate the target person on the basis of the target feature quantity.