To detect the distance between an interacting device and an operator by utilizing a voice input means and a voice output means, which are originally equipped for interactive processing.

A receiving terminal 20 includes a microphone 207 for inputting voice, and a speaker 208 for outputting voice. Based on noise information which is generated in surroundings, and which is obtained by the microphone 207, false noise for detecting distance is output via the speaker 208. Reflective sound information including a corresponding amplitude or frequency, by reflective sound of the false noise from an object, which is input via the microphone 207, is obtained. Based on the obtained reflective sound information, predetermined calculation processing is performed, and distance to a visitor M is detected by presuming that the object is the visitor M. Based on the detection result, receiving processing by interaction with the visitor M is started.