This article is a review of important developments in psychological and physiological acoustics, primarily in the United States in the period 1920–1942. It includes a reference to the early work of Harvey Fletcher and his co‐workers at the Bell Telephone Laboratories on the psychoacoustics of speech and hearing, leading to the definitive exploration of the ’’auditory area’’ and the development of the audiometer. The replacement of the Weber–Fechner psychophysical law by the Stevens power law is mentioned. In the domain of physiological acoustics the importance of the investigations of Békésy, Wever and Bray, and Galambos on acoustical nerve transmission is emphasized.