A digital master hearing aid configured around a programmable digital filter was used to simulate hearing aids prescribed by four different procedures. The prescriptive procedures were modeled on those developed by Skinner, Byrne and Toonison, Lybarger, and Levittet al.Real‐time simulation allowed for adaptive paired‐comparison testing to be used in evaluating the prescribed hearing aids. Data were obtained for three signal levels corresponding to input levels of 60 and 70 dB SPL and an output level corresponding to the subject's most comfortable loudness level. Speech discrimination scores were obtained for each simulated hearing aid at each signal level, as well as paired‐comparison judgments of relative intelligibility and overall quality. No single prescriptive procedure was found to be uniformly superior to the other procedures considered. Differences between procedures were largest at low signal levels and smallest at the subject's most comfortable level. [Research supported by NIHR.]