Experiments were performed to measure suprathreshold loudness adaptation at 500 Hz using a heterophonic listening condition in order to reduce binaural interaction. The adapting stimulus was presented at 70 dB SPL for 7 min. A long (3000 msec) and a short (300 msec) comparison stimulus were chosen to delineate the possible influence of the duration of the comparison stimulus itself on the magnitude of the loudness change measured. No loudness adaptation was observed during these experimental conditions. We interpret these results as corroborating similar findings in another laboratory indicating essentially no loudness change under perstimulatory test conditions in which binaural interaction is reduced. During the initial experiment an apparent “enhancement” of loudness was observed during the adapting period when a train of short pulses (300 msec each) was used as the comparison stimulus. In a second experiment, results suggested that, in fact, there is a loudness disparity between a pulse train and a continuous signal. For conditions where the loudness of a single short pulse is compared to a continuous signal, however, no loudness disparity was observed.