Measurement of auditory distortion with relation between harmonic distortion and human auditory sensation

Total harmonic distortion (THD) is commonly used to evaluate the "sound quality" of a sound system. As a matter of fact, it merely represents physical meaning and does not correspond to real hearing sensation. This paper discusses the following studies: (1) experiments that yielded a set of curves which represent the threshold of the human ear to various orders of harmonic distortion and, (2) electronic equipment with special weighting networks that are designed according to the curves for measuring the distortion of a sound system. The measured data is dubbed as the "Auditory Distortion Figure," It reflects the real sensation of the human ear that responds to the harmonic distortion.