A method for controlling a frequency response having a bell-shaped amplitude characteristic of a filter that is configured to process an audio signal includes preparing a high-frequency parameter related to a high-frequency side characteristic on a high-frequency side of the frequency response, and a low-frequency parameter related to a low-frequency side characteristic on a low-frequency side of the frequency response, independently changing the high-frequency parameter or the low-frequency parameter in accordance with a first change instruction, changing both of the high-frequency parameter and the low-frequency parameter in conjunction with each other in accordance with a second change instruction, and controlling a slope on the high-frequency side and a slope on the low-frequency side of the bell-shaped amplitude characteristic of the frequency response, by using the high-frequency parameter and the low-frequency parameter.