 Weber was able to define absolute and difference threshold statistically which lead to the establishment of Weber's Law and the concept of just noticeable difference to describe threshold perception of stimuli.Following Weber's work, Gustav Fechner, a pioneer of psychophysics, studied the relationship between the physical intensity of a stimulus and the psychologically perceived intensity of the stimulus.Comparing the measured intensity of sound waves with the perceived loudness, Fechner concluded that the intensity of a stimulus changes in proportion to the logarithm of the stimulus intensity.