谐波失真（THD）指原有频率的各种倍频的有害干扰。放大1kHZ的频率信号时会产生2kHZ的2次谐波和3kHZ及许多更高次的谐波，理论上此数值越小，失真度越低。-Harmonic distortion (THD) refers to the original frequency range of frequency doubling of harmful interference. The frequency of signal amplification 1kHZ produce 2kHZ 2 harmonic and 3kHZ and many more times the harmonic theory, the smaller this value, the lower the distortion.