Click here to purchase the entire book in PDF format. Method of Adjustment (MOA) There is another way of doing the test for JND in loudness I described in the second on TAFC tests. You could give the subject a reference stimuli (play a tune at a certain level) and give the person a second stimuli (same tune, different level) and a volume knob. Ask them to change the volume of the second stimuli so that it matches the reference. Repeat this test over and over and average your results. In this test, the subject is adjusting the level, so we call the test a method of adjustment (MOA) test. If you put a bunch of psychologists and audio people in a room, they'll get into an argument about which is better, a TAFC or an MOA test. The psychologists will argue that an MOA test gives you a more accurate result. The audio people will tell you that the MOA test is less tiring to perform. There is a small, sane group of people that thinks that both types of tests are fine - pick the one you like and use it.