| 摘要 |
A variable control device in a learning system and a controlling method thereof are provided to prevent sudden change of a volume level due to a mistake on the volume control by controlling the volume level outputted to the speaker in two stages. In a learning system(300), a plurality of learning devices are connected with an electrical signal. A mode setting unit sets up the mode for controlling the displacement of a second volume level through the control unit. A displacement detector(90) detects the increase and decrease of the level displacement of a first volume level by the operation of a first volume level controller in an amplifier system(400) according to the control mode. The controller outputs the control signal for variably controlling the whole range of the level displacement of the second volume through a second volume level changing unit with regard to the level displacement of the first volume. A control system(100) includes a D/A converter. The D/A converter converts the control signal outputted from the controller into a digital/analog signal. |
