Over a range of 50 dB, the loudness of a 100‐Hz tone was measured in the presence of a broadband noise with a low‐frequency cutoff at 200 Hz. The noise was varied in intensity along with the tone so that the signal‐to‐noise ratio remained constant at either 0 or −10 dB. Listeners judged the loudness of the tone by loudness matching, magnitude estimation, and magnitude production. The noise markedly decreased the tone’srateof loudness growth but not therangeover which loudness grows. The overall decrease in steepness of the 100‐Hz loudness function was greater than that previously reported at higher frequencies. It is hypothesized that the decrease was greater because the spread of excitation at 100 Hz was more effectively contained than at higher frequencies. Support for this hypothesis is given by measures of intensity discrimination at 100 Hz.