A signal processing apparatus comprising: a processing unit configured to execute an equalizer module for processing a signal, the equalizer module performing signal processing according to a frequency characteristic indicated by a given equalizer curve, the given equalizer curve being determined based on a reference equalizer curve prepared in advance; and a processor, characterized in that the processor is configured to: receive a single magnification parameter that is a multiplier to be multiplied with each of gain values of frequencies corresponding to a plurality of control points in the reference equalizer curve; change each of gain values of frequencies corresponding to the plurality of control points in the given equalizer curve by multiplying each of the gain values of frequencies corresponding to the plurality of control points in the reference equalizer curve with the received single magnification parameter, and determine respective gain characteristics of frequency domains other than the control points in the given equalizer curve in accordance with a change in each of the changed gain values of the control points and on the basis of each of Q quality factor values of the plurality of control points. a processing unit configured to execute an equalizer module for processing a signal, the equalizer module performing signal processing according to a frequency characteristic indicated by a given equalizer curve, the given equalizer curve being determined based on a reference equalizer curve prepared in advance; and a processor, characterized in that the processor is configured to: receive a single magnification parameter that is a multiplier to be multiplied with each of gain values of frequencies corresponding to a plurality of control points in the reference equalizer curve; change each of gain values of frequencies corresponding to the plurality of control points in the given equalizer curve by multiplying each of the gain values of frequencies corresponding to the plurality of control points in the reference equalizer curve with the received single magnification parameter, and determine respective gain characteristics of frequency domains other than the control points in the given equalizer curve in accordance with a change in each of the changed gain values of the control points and on the basis of each of Q quality factor values of the plurality of control points. receive a single magnification parameter that is a multiplier to be multiplied with each of gain values of frequencies corresponding to a plurality of control points in the reference equalizer curve; change each of gain values of frequencies corresponding to the plurality of control points in the given equalizer curve by multiplying each of the gain values of frequencies corresponding to the plurality of control points in the reference equalizer curve with the received single magnification parameter, and determine respective gain characteristics of frequency domains other than the control points in the given equalizer curve in accordance with a change in each of the changed gain values of the control points and on the basis of each of Q quality factor values of the plurality of control points.