lossyWAV 1.2.0 Development Thread
Reply #183 – 2009-02-05 08:11:20
... The Sole Reason for me to up the trials per session from 20 , to 50 , to 80, is to have Fatigue & Focus play a bigger role , & indeed they do. ... Because of these things and the extreme pain of such an ABX test I think it should be left to the tester to a large extent how to conduct the test. But even with this in mind I think it's not totally correct the way you do it. Your last tests look a bit like continuing the test so far until you have reached a rather long sequence of more or less uninterrupted hits providing a rather low percentage of probabability for testing. While this still gives information that you can hear a difference (and may be enough for our needs here - but I'm not sure) it is not totally convincing. The longer your test the more likely is that such a sequence of hits happens by chance. You shouldn't try and try just until a guessing probability is reached you consider low enough. Using this as a test stopping criterion is a method for giving your test results a positive bias. I'd feel more comfortable if you would make sure good listening conditions for you in another way, for instance doing a long warm up listening to just A and B before starting the real X/Y gueeses. And/or - as you seem to feel more comfortable with long test sessions - decide for a long test sequence of say 40 trials or whatever you like best. Use whatever listening condition is best for you. But the number of trials should be fixed. Other than that thanks again for testing. We now know you didn't use noise shaping to get at your last results. And this brings at least better results than the noise shaping of 1.1.2. We don't know however whether Nick.C's noise shaping fix improves the situation. I know it's hard but can you please test your samples using Nick.C's current version (EDITED:) 1.1.2d and leave noise shaping as defaulted?