| 摘要 |
PURPOSE:To distinctly transfer acoustic information to a driver even if it is affected by an external noise, by constituting so that sound volume to be outputted is increased by being interlocked, when said information has been set to a state which is susceptible to influence of the external noise. CONSTITUTION:When a door of an automobile is closed, a door switch 18 is opened, and a transistor TR19 is in an on-state. Accordingly, a resistance 21 is connected in parallel with voltage dividing resistances 16, 17, and a part of an input current to an amplifier 13 is shunted, therefore, an output of a loudspeaker 12 is suppressed. When the door is opened, the door switch 18 is closed, the TR19 becomes an off-state, and the resistance 21 is disconnected. Accordingly, an input to the amplifier 13 is increased, and a sound output from the loudspeaker 12 is also increased. Therefore, it is possible to offset influence of an external noise caused by opening the door. |
