To change a value of a DSP parameter in a DSP setting screen, a user selects from parameter operators a parameter value to be changed. In an image picture displayed on the DSP setting screen, a size, a color, and the like corresponding to substance of the pertinent parameter are changed according to the value of the parameter. The user can visually perceive effect of the value of each DSP parameter on an acoustic effect and can easily change the value of each DSP parameter.