In this exemplary embodiment, the noise/device property removal means 201 removes such noise and device property from the observation acoustic signal. With this structure, the acoustic property calculation means 103 can use the observation acoustic signal from which the noise and device property are removed.

A specific method of noise/device property removal is, for example, a method of transmitting the transmission acoustic signal to two locations of the head of the user and observing the respective signals. By performing subtraction on two observation acoustic signals observed from the two locations of the head of the user, it is possible to keep only the biometrics-derived acoustic property dependent on the positional difference between the two locations of the head and remove noise and device property not dependent on the positional difference. The method of observing the acoustic signals at the two locations may be, for example, a method whereby one acoustic signal observation means 102 performs observation twice to obtain two observation acoustic signals, or a method whereby two acoustic signal observation means 102 each perform observation once to obtain two observation acoustic signals. For example, the acoustic signal transmission means 101 and the acoustic signal observation means 102 may transmit the acoustic signal to each of the right and left ear canals and/or pinnae and perform observation, to obtain two observation acoustic signals. The noise/device property removal means 201 may remove noise and device property, using the two observation acoustic signals observed in such a way.