Because when you DBT, some people will hear differences where none exist and some will not hear differences when they do exist. This makes any so-called scientific study invalid since it cannot show which is right - those wo say that there are no differences and ones who say there is. It is much harder (maybe impossible) to prove by testing that you cannot discern differences than to say you can.
Why? I think it's because the brain will discern differences in sound when it wants to. It's part of our survival instinct (a police officer chasing an armed person can think a twig snapping is a gun being cocked and will react defensively). Also, not to pick on Twl, if you take Twl and his co-workers informal scientific, but fun, experiment: if I were to tell each of them that I replaced one component when I in fact did not, I would bet that more than one (maybe all) would have identified something as being changed. It's the way the brain works - if it thinks there is a difference, it will try its best to find one (especially with the peer-pressure factor thrown in). Conversely, if it thinks there is no difference, whether out of prejudice or justification, then it won't find one. But if you tell the brain there may be or may not be a difference, then it's up to the listening skills to be invoked - and that too varies wildly among people; to the point where if someone hears a difference in a component might not (and vice versa) in a DBT. That's the controversy IMO.
Why? I think it's because the brain will discern differences in sound when it wants to. It's part of our survival instinct (a police officer chasing an armed person can think a twig snapping is a gun being cocked and will react defensively). Also, not to pick on Twl, if you take Twl and his co-workers informal scientific, but fun, experiment: if I were to tell each of them that I replaced one component when I in fact did not, I would bet that more than one (maybe all) would have identified something as being changed. It's the way the brain works - if it thinks there is a difference, it will try its best to find one (especially with the peer-pressure factor thrown in). Conversely, if it thinks there is no difference, whether out of prejudice or justification, then it won't find one. But if you tell the brain there may be or may not be a difference, then it's up to the listening skills to be invoked - and that too varies wildly among people; to the point where if someone hears a difference in a component might not (and vice versa) in a DBT. That's the controversy IMO.