Vehicle sound system automatically reducing volume during mobile phone call

Disclosed is a vehicle sound system automatically reducing the volume during a mobile phone call. When the call in a vehicle is detected, the vehicle sound volume can be reduced automatically, the volume can be recovered when the call is ended, and the defects that the attention of a driver is distracted due to manual silencing are overcome. A signal sensing module comprises an antenna, a frequency divider, a mobile phone signal processor and a frequency modulator and is used for sensing and recognizing different mobile phone network bands and modulating the frequency as digital signals; a processing module comprises a single chip microcomputer and is used for receiving the digital signals and outputting volume reducing signals; an executing module comprises a signal amplify circuit, a delay circuit, a conducting circuit and a drive circuit and is used for reducing the vehicle sound volume; a mobile phone signal is divided into four paths, one path is processed through TD-SCDMA, and the frequency is modulated through the TD-SCDMA; one path is processed through WCDMA, and the frequency is modulated through the WCDMA; one path is processed through CDMA 2000, and the frequency is modulated through the CDMA 2000; one path is processed through GSM, and the frequency is modulated through the GSM; the mobile phone signal is integrated and output after digital processing to a sound volume adjusting circuit via the signal amplify circuit and the drive circuit.