以频率的常用对数为横坐标，声强级为纵坐标，绘出不同频率的声音与 10000Hz 的标准声音等响时的声强级与频率的关系曲线，得到的曲线称为等响曲线。Take the logarithm of frequency as the abscissa and the sound intensity level as the ordinate, and draw the relationship curve between the frequency and the sound intensity level when the sound of different frequencies and the standard sound of 10000 Hz are equal-loudness.Such curve is called the equal-loudness curve.