Harmonic Distortion Perception Threshold

One of the quality factors of almost every professional audio instrument is the total harmonic distortion (THD) factor. In view of attempts to reduce it to the smallest possible values, a question comes up: what is the real human threshold of perceiving harmonic distortion? In an effort to examine the perceptibility of harmonic distortion we conducted subjective tests on a great number of examinees using different music samples. For this purpose we developed a test method that includes listening to different music samples containing different levels of harmonic distortion, using a special graphic user interface in order to keep the handling and reproducing the samples as simple as possible as well as to prevent weariness of the examinees.