What's the problem with double-blind testing?
Reply #68 – 2005-10-22 00:00:11
So, if we're adding noise to a signal that someone is trying to interpret, it's pretty obvious that it's going to require more processing. Do you find it easier to understand speech in a crowded bar or a quiet room? This is why they put up acoustic panels in auditoriums; too much reverberation acts like noise and makes speech more difficult to understand. This isn't really debatable. This is also what isn't debated. Audible differences lie within the scope of an ABX-test.What is in question is whether or not noise that is below the threshold where you can actually hear it still has an effect on processing, and what research is showing over and over is that whether or not something is directly perceived has very little to do with the underlying processing. The brain is processing the sounds into a "reality" for your conscious mind to act on, and does not want to bother you with unimportant details that might distract you. What if every stimuli registered by your senses was consciously perceived!! Well, yes, this is what psycho-acoustic models try to take advantage of.Imagine walking blindfolded into a large room with sound reflective walls. You instantly become aware of the rough dimensions of the room, but you don't hear every echo of every footstep. A blind person would be able to "hear" in much greater detail, and in fact claim to be able to almost "see" the room. This is the kind of thing that the subconscious mind is constantly doing for us in the background, and what finally gets presented to our conscious mind is rather independent of what processing was required to achieve it. I admit that without at least a working knowledge of the literature, this may seem counterintuitive. No this is not what sounds counterintuitive. It sounds counterintuitive that my brain would have to work harder on a lossy compressed signal than on the original. Also note that duff and you are not helping each other, because you say the brain needs to work harder to filter out the noise, and duff says the brain needs to work harder to somehow interpolate the signal and thus creating info. While I might be misunderstanding duff and I found your explanation more plausible, this still doesn't keep me from wondering why it would require more effort. In both cases, all the info must be processed and a decision must be made if it is passed through to my conscience or not. But for as long as both signals carry the same amount of info then the same processing "power" is required, independantly of what my consious receives. Now I cannot say if a noisy signal would contain more info than a clean one (probably yes, but can we measure this? if as you say a lossless compressed wav is a reasonable guess of the amount of info in a signal then in the 3 tests I have done quickly now the recompressing the lossy files to lossless results in a smaller size than the original thus indicating a smaller amount of info), but all I am asking is some proof for these claims. When people start using phrases like "It goes without saying" and "uncontroversial" I always immediately start asking myself: "Is that so?". And since these claims are made so a hard I don't think it is unfair of me to ask for some sources that confirm this. Enfin...opinions, and the free and lively interchange of ideas is what this board is all about. But I don't think it would hurt for a slightly more flexible attitude to prevail (and it would certainly reduce the possibility of many egg covered faces in the future). Oh I'm flexible and I wasn't throwing with eggs, but I can't do much with mere assumptions if that is all they are. If you say I can't trust my intuition in this area, I have no reason to believe one assumption more than the other if neither is backed with any kind of proof. This has nothing to do with flexibility, but practicality.Have a good weekend! You too.