Weber fractions in audition are computed from intensity, not decibels

Evidence

Now that the weightlifting analogy provides an intuition of Weber’s law, we can apply the same concept to an intensity discrimination experiment. Note that in these experiments, the size of the stimulus is characterized by the intensity (I) of the sound in W/m2, not the decibel value of the sound, as this is important for understanding and interpreting Weber’s law. Here, the JND is defined as DI, or the difference in intensity between two sounds. Applied to intensity discrimination, then, the Weber fraction is DI/I. — Jennifer Lentz, Psychoacoustics- Perception of Normal…, 807

Categorization

• DEFINE: Defines how the Weber fraction is computed for intensity discrimination: JND is the intensity difference, the fraction is that difference divided by the baseline intensity.