leoboiko’s computing log

Why do variable resistors come with nonlinear tapers? Well, as it turns out, human physiology has a weird way of perceiving changes in signal intensity, such as sound and light intensities. For example, you may think that if you doubled the intensity of sound or light, you would perceive a doubling in sound and light. Unfortunately—at least in terms of intuition (not in terms of safety control for our brains)—humans do not work this way. In fact, our perceptions of sight and sound work as follows: Perceived loudness/brightness is proportional to log₁₀ (actual intensity measured with a nonhuman instrument). Thus, if you are building an amplifier for a set of speakers or building a home light-dimming circuit, it would be wise to use a variable resistor with a nonlinear taper.

(From: Practical Electronics for Inventors, Paul Schers)