The decibel changes required to halve and to double the apparent loudness of a white noise were determined at nine sound pressure levels by 36 subjects. The subjects adjusted the level of the noise by means of an improved control—a “sone potentiometer” whose angular turn is roughly proportional to the loudness produced. An attempt was also made to measure and control some of the biasing factors that affect loudness estimations. Results: the median decibel changes required to produce a 2:1 loudness ratio ranged from 6 to 10 db, approximately.