当信噪比低，小信号输入时噪音严重，在整个音域的声音明显变得浑浊不清，不知发的是什么音，严重影响音质。信噪比的大小是用有用信号功率（或电压）和噪声功率（或电压）比值的对数来表示的。-When the signal to noise ratio is low, serious small signal input noise, the sound of the entire range becomes significantly turbid, I do not know what made the sound, seriously affecting the sound quality. Size is the number of the signal to noise ratio by the ratio of desired signal power (or voltage) and the noise power (or voltage) represented.