| 摘要 |
PURPOSE:To automatically attenuate a sound volume of an audio device or make it zero at a specific place where the sound volume is to be attenuated or made zero (for example, at a crossing, a toll gate, a gas station, etc.). CONSTITUTION:In a system comprising a navigation device for displaying a position of an automobile on a map by means of automobile position detection and a mounted audio device, longitude and latitude of a place where a sound volume of the audio device is to be attenuated or made zero is preset in a navigation system control part 12. A distance between longitude and latitude of a current automobile position and the preset longitude and latitude is monitored, and when the distance is at a constant value or less, an instruction to attenuate the sound volume or make it zero is output to the audio device to attenuate the volume or make it zero, while when the distance returns to a constant value or more, an instruction to recover the volume is output to the audio device to have it returned. |
