Abstract: In an acoustic apparatus, one or more front and rear speakers are provided in a space such as a car compartment. The volume levels of the audio signals output from the speakers are controlled by the volume control unit. Also, the valance between the volume levels of the audio signals from the front speaker and the rear speaker is controlled by the balance control unit. The balance control unit generally controls the balance according to the input by a user. To the front speaker or the rear speaker, an external audio signal can be supplied. When the external audio signal is supplied to one of the front speaker and the second speaker which has not been attenuated by the balance control device and the balance control device attenuates the volume level of said one of the front speaker and the second speaker, the volume level of the audio signal is attenuated. Therefore, the external audio signal becomes easy for the user to hear.

Abstract: An electronic device does not carry out control operation corresponding to a signal from an operation button which is kept in pressed state when electric power is supplied. When electric power is supplied, the voltage changing depending on open and closed state of switches SW1 to SW4 corresponding to operation buttons to be manipulated is judged to be a specified value or not. When the voltage is not judged to be specified value, the control unit does not carry out control operation corresponding to the signal from the operation button that has been in pressed state.

Abstract: An electronic device does not carry out control operation corresponding to a signal from an operation button which is kept in pressed state when electric power is supplied. When electric power is supplied, the voltage changing depending on open and closed state of switches SW1 to SW4 corresponding to operation buttons to be manipulated is judged to be a specified value or not. When the voltage is not judged to be specified value, the control unit does not carry out control operation corresponding to the signal from the operation button that has been in pressed state.

Abstract: In an acoustic apparatus, one or more front and rear speakers are provided in a space such as a car compartment. The volume levels of the audio signals output from the speakers are controlled by the volume control unit. Also, the valance between the volume levels of the audio signals from the front speaker and the rear speaker is controlled by the balance control unit. The balance control unit generally controls the balance according to the input by a user. To the front speaker or the rear speaker, an external audio signal can be supplied. When the external audio signal is supplied to one of the front speaker and the second speaker which has not been attenuated by the balance control device and the balance control device attenuates the volume level of said one of the front speaker and the second speaker, the volume level of the audio signal is attenuated. Therefore, the external audio signal becomes easy for the user to hear.