hirsch;179123 Wrote: > You have a difference. You don't know if the difference is due to > physical or psychological influences. DBT can help rule out > psychological influence. You've run DBT. Congratulations! Your > difference is likely not due to psychological influence. >
Correct. hirsch;179123 Wrote: > If you hear a difference, and can go back and measure a difference in > the stimuli, why bother with DBT? It's not a necessary control at that > point. You've got a measurable difference, and you can hear it. Done. > You are making a value judgment, and that is fine. However, if you do not do DBT then you have not demonstrated that the difference you hear is really there. I am in no way saying that you should do DBT if you are satisfied that you hear a difference. hirsch;179123 Wrote: > The other main problem with DBT is the misinterpretation of negative > results. The absence of a positive finding with DBT does not imply a > negative result. It simply indicates that no difference was found in > that test situation. So what? People look at random results in a DBT, > and suggest that there is no difference in the stimuli. However, > psychological factors work both ways, and can mask real differences as > well as producing artifical ones. What steps were taken to insure that > the negative result is real? > Good question. Meaningful DBT requires a statistically significant sample size (many repetitions with many different pairs of ears). hirsch;179123 Wrote: > Here's a question that you need to ask in interpreting DBT: Is there > anything in these results that are different than those that would be > produced by a person with hearing loss? Bear in mind that a random > result could be produced by someone with profound hearing loss, even > when a large audible difference is present. So, in any given test, > we've got to ask what steps were taken to insure that small audible > difference are accurately detected as a bare minimum before taking any > negative DBT results seriously. Were positive control groups, with > known audible differences, part of any DBT experiment? Without them, a > negative DBT is meaningless. > Positive controls should not be necessary with a statistically significant sample of listeners, chosen from the general population at random. Where statistically significant sample sizes are impractical (most of the time), then positive controls would add some credence. However, when we take one individual who claims to hear a difference and find that he cannot identify it in a DBT, then we have learned something. hirsch;179123 Wrote: > As long as DBT is used properly, as a control condition to aid the > interpretation of positive results, it's an important and useful test. > However, general misunderstanding of its limitations, by proponents and > opponents of DBT, as evidenced by the quote above, has made it fairly > useless as a tool in audio. The debate is much ado about nothing. DBT > can help interpret an apparent positive difference. That's it. No > application to negative results whatsoever. I fail to see how the quote you reference displays a general misunderstanding of DBT limitations, as the poster is merely stating that verifying that someone can hear a difference through DBT proves that the change is audible, rather than psychological. If I read your post correctly, you say that that, and only that, is what DBT can do effectively. -- jeffmeh ------------------------------------------------------------------------ jeffmeh's Profile: http://forums.slimdevices.com/member.php?userid=3986 View this thread: http://forums.slimdevices.com/showthread.php?t=32352 _______________________________________________ audiophiles mailing list audiophiles@lists.slimdevices.com http://lists.slimdevices.com/lists/listinfo/audiophiles
