The present invention relates to a device and a method for detecting a change in characteristics of a hearing aid and informing a user of the change. In one embodiment, a first input audio signal and an second amplified audio signal transmitted from the a hearing aid are received via a communication unit. Simulation is conducted of amplifying of the first input audio signal according to pre-stored auditory information stored in advance, and the processed simulated amplified first input audio signal is compared with the amplified audio signal. An alarm signal is output when a difference between the processed simulated amplified first input audio signal and the second amplified audio signal is greater than a predetermined threshold.