When there is an incoming call, a mobile terminal device detects ambient sounds by a microphone. A filter separates the detected ambient sounds into a speech component and a non-speech component. An analysis section analyzes which one of the speech component and the non-speech component is the dominant component. A decision section selects a ringing tone generating section, a vibrator or a light emitting section based on which one of the speech component and the non-speech component is the dominant component and the volume of that dominant one. The selected ringing tone generating section, vibrator or light emitting section makes ringing to inform a user of the incoming call.