The results of psychophysical tests on the auditory sensory system usually show much more variability than experiments involving only physical measurements of sound waves. This has resulted in the general impression that the variance of measurements of the auditory threshold and other psychoacoustic measurements is largely due to the inability of the observers to give consistent responses. This paper reports the results of a series of threshold measurements made under carefully controlled conditions and accompanied by search tube measurements of the sound pressures in the ear canals of the observers. The small variances obtained under certain conditions suggest that the large variability oftentimes experienced in psychophysical work is partly due to inadequate techniques for measuring the levels of the stimuli that activate the sensory system.