Auditory‐flutter fusion (AFF) threshold measurements were made for pure tones and white noise by varying the rise and decay time. The tests were conducted with trained, normal‐hearing subjects and also those with pathological ears. Off time was the major factor in determining the AFF threshold. The off time required to obtain AFF threshold was dependent upon the rise and decay time and followed a definite pattern referred to in the derived equation. There was no relationship between on time and AFF threshold. Other variables such as testing intensity level, interruption rate, and stimulus components did not provide any statistically significant alteration of AFF threshold. AFF thresholds were similar for both normals and pathologicals with and without abnormal adaptation.