Early in the psychophysics phase of his illustrious and varied scientific career, Joe Zwislocki recognized that loudness is of key importance for understanding signal processing by the auditory system. To better comprehend just how loudness can be incorporated into basic auditory theory, Joe sought to determine the loudness‐intensity relation down to near threshold levels. Together with Hellman, this aim motivated the development of absolute magnitude‐scaling procedures. Later, Joe demonstrated that absolute scaling yields results compatible with nonmetric measures of loudness additivity. His search for a comprehensive theory of auditory function led him to deduce that both the observed proportionality between loudness and sound intensity near threshold and the compressive nonlinearity in the loudness function at moderate‐to‐high levels are generated by the peripheral auditory system. These innovative concepts were incorporated into his theoretical analyses of temporal summation and central masking. They also provided the basis of a loudness model formulated to describe loudness growth in quiet and in noise. Not only are Joe Zwislocki’s extraordinary insights compatible with recent loudness measures, his loudness model can be extended successfully to predict the growth of loudness characteristic of cochlear‐impaired hearing. [Work supported by NEDO, Japan.]