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Biophysics & Medical Physics

Weber-Fechner Law

A psychophysical law stating that human subjective sensory perception is proportional to the logarithm of the physical stimulus intensity.

Governing formula p = k ln(S / S₀) (Perceived Sensation = k ln(Stimulus Intensity))
SI unit Psychophysical Scale (e.g. dB, Stellar Magnitude)

In depth

Explains logarithmic human sensory response across vision, hearing, and touch. Doubling physical stimulus intensity produces an additive step in perceived sensation, protecting sensory organs across wide dynamic ranges.

Examples in the real world

Human loudness perception measured on logarithmic decibel (dB) scales and stellar visual brightness magnitudes.