The measurement techniques used in post-stimulatory masking experiments were evaluated in the light of published results on temporal integration, critical bands and transient responses. A new measurement technique was proposed which used a probe tone of a much longer duration than is normal. This technique was designed in order to avoid the transient responses generated with the normal technique. Preliminary tests were carried out to determine the best operating conditions, and the new measurement technique was experimentally validated. The post-stimulatory masked thresholds of a probe tone masked by another tone were measured. In the first experiment the post-stimulus time was held constant and the probe tone frequency was varied. The results measured were in agreement with other experimental results. In the second experiment the frequency of the probe tone was held constant and the post-stimulus time was varied. This experiment was repeated for three levels of the masking tone. The results differed from previously published findings and the ensuing implications of these results are discussed.