What is total harmonic distortion (THD)? — Audiophile ON

Distortion of a sound is exactly what it sounds like. It is extra being put into the final output signal and making it sound wrong, i.e., distorted from its pure form.  

Audiophiles work hard at all stages of their setup, whether it be with headphones and earphones right up to full-blown audiophile-grade HiFi speakers, to reduce distortion to the sound signal wherever possible, and today we are going to look at the effect of Total Harmonic Distortion or THD as it is commonly represented.

In your audio setup, you will find total harmonic distortion in the amplification components, whether in a pre-amplifier or amplifier section.  

What is Total Harmonic Distortion (THD)?

Distortion is one of the most significant factors in producing the best sound possible.

Total Harmonic Distortion is a value of measurement given to the difference between the input signal and the output signal from the amplifier.  

In other words, how close is the signal that comes out to the signal that went in? In this regard, we can consider that the lower the THD figure, the better the sound quality, as this would mean the audio signal is in a purer form.  

When looking at manufacturer specifications or frequency graphs relating to the amplification section of a particular audio equipment piece, you will commonly see THD listed as a %.  

The lower the THD percentage, the better. In an ideal situation for use with headphones, speakers, and earphones, you would be looking for a total harmonic distortion level as close to zero as possible.