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In Reply to: RE: Olive and Toole specifically say in the paper – no, they don’t!!! posted by KlausR. on January 13, 2008 at 05:49:21
Let's deal with the issue of applicability of the Olive and Toole paper to stereo situations first.
1- Accepting that the tests in the paper did not involve stereo and that Olive and Toole did not research the stereo issue before writing the paper does not make Everest wrong. Everest wrote his book after the paper. My edition is 1994 and that would give them a 5 year window in which to have looked at it and reported on that situation while allowing Everest to be correct. You can't use a cut it off date of the original paper in this case.
2- Everest could be reporting on a statement made by Olive and/or Toole in personal conversation/correspondence or a remark made in answer to a question at a paper presentation. The only reference he cites is the 1989 paper and, if that is the case, he certainly should have cited a personal communication of some sort, but it's not outside the realm of possibility and Everest may not be reading something into that paper which is not there. He at least deserves the benefit of the doubt before you absolutely condemn him on that point.
Now to your contention that I can't rely on the Everest statement:
There are 3 possibilities:
1- Everest is correct that the 1989 paper can be applied to stereo situations and there is evidence to support that view but it's not contained in a paper you've read. You've criticised Everest before for not citing as many documents as you've read but can you honestly say you've read every document there is? I don't think you can categorically state that Everest is wrong, just as I can't categorically state that he is right.
2- Everest is correct about the results being able to be applied to the stereo situation but you are correct about there being no evidence to support the claim. The one piece of research I did in relation to eye testing for a research project required for a post graduate qualification ended up confirming a recommendation made by 2 professors in a published document. When I presented that research at a conference chaired by one of the professors I got the opportunity to ask him about his evidence for that recommendation since none was cited. He said there was none and that they had based their recommendation on clinical experience. The recommendation was reasonable and people were relying on it but I had wanted to know whether it was justified because of the potential costs of following it. I ended up with a study that showed it was. So, it's quite possible that professionals working in an area can come up with recommendations based on 'gut feel' and their experience and be correct. This could be the case here.
3- Everest has no evidence and his statement is wrong.
Those are the 3 possibilities. There are no other alternatives. Your position is that I shouldn't rely on the statement because there is no evidence to support it but really all you can say is that you haven't found any evidence to support it. What is obvious is that there is a possibility that there is evidence you don't know about, that there is a possibility that the statement is correct but there is no documentary evidence, and there is a possibility that the statement is simply wrong. How do I go about choosing between those possibilities?
Well, from my perspective I first consider whose "word" I would give more credence to, that of a professional and published author in the field in a book that is popular and durable enough to have gone through 4 editions now or that of an enthusiastic and committed amateur who is widely read but has not conducted research or published or worked professionally in the field. My choice in that situation will always be the professional. Second, I consider the reasonableness of the claim. It seems reasonable to assume that things will behave similarly in a stereo situation and that the data can be used in that situation. I know of nothing to suggest that things won't work that way so while I may not have confirming research, I don't know of any that would disconfirm it. On the other hand, I also have seen statements from a number of people who have followed Everest's recommendation and who found it worked in practice. I therefore tried it myself and found that it worked in practice for me as well. Each individual practical report may be anecdotal but they all support Everest and that counts for something too.
So, if it comes down to a choice between deciding to treat early reflections based on recommendations by a professional with a book that has stayed in print for more than a few years and through several editions and anecdotal evidence from those who have tried it, or instead accepting your statements that there is no evidence at all to support it (not quite true because anecdotal evidence does have some value even if not the same value as a peer reviewed paper) and your oft repeated statement that no-one has said it is necessary, I will always choose the professional recommendation. Yes, there is a possibility that it may be wrong but there's also a possibility that you are wrong. In my view the expert opinion of a professional backed by consistent anecdotal reports should always outweigh the opinion of a well read amateur with no practical experience in the field and who seems to be the only person holding his particular view. I would also recommend that others follow Everest's recommendations rather than yours for exactly the same reason.
Finally, on the issue of whether reflections are detrimental or not:
1- the fact that Olive and Toole don't categorically state that they are does not mean that they're not detrimental. They researched the effect of reflections on our perception and reported that. Whether or not the effect will be detrimental depends on circumstances and what goals one has in a given situation. I believe Olive and Toole were correct in not making a categorical statement about whether or not the effects were detrimental and I would not expect to see such statements in most research papers. I would not expect to see such a statement unless the paper concerned perception in a single, clearly stated specific situation. Olive and Toole's paper concerns the general situation.
2- you say "In any case this scenario has to be experimentally investigated and in no case conclusions retaling to stereo system/multiple reflections scenario can be drawn from the single loudspeaker/single reflection situation." I say you're wrong. First it does not HAVE TO BE investigated. It would be nice if it was (and it hasn't already been but you haven't read the results which remains a possibility) but there's no "have to" about it. Secondly, while no conclusions may be able to be drawn, inferences can certainly be drawn and there's nothing wrong with individuals testing those inferences. No one has to wait on the sort of evidence you want before trying things for themselves and seeing whether or not they prefer the results, especially since there are clear professional recommendations that it is beneficial and those are supported by what you regard as merely anecdotal evidence by others who have tried and, it seems, universally been happy with the results. Research that confirmed the value of the recommendation and the experience of those who have tried it would be nice but there are probably a lot more areas awaiting research to clarify things that are a lot more unclear to make it a pretty sensible conclusion that we're better off just accepting the anecdotal evidence here until something that looks like it might disconfirm that arises and spend the research time, money and effort elsewhere.
I think this really should be my final word on the matter. We can't resolve the evidence/lack of evidence dispute to our mutual satisfaction and, even if we could, there's still the question of whether or not it's beneficial to treat reflections and, on a more general level, rooms as a whole. As I've pointed out above, there are professional recommendations and anecdotal evidence supporting treatment and there seems to be only your view that there is no evidence indicating a need for treatment supporting the opposing view. I've stated how I would make a decision in that situation and what I would recommend to others in the situation.
Regardless of which side any reader of this thread accepts there is a possibility that they will make the wrong choice and they can't escape that. The question is whether the risk of making a mistake if in deciding to treat your room is greater than the risk of a mistake if you decide not to. You're certainly no worse off if you decide not to so that's a no lose decision. It's also a no win decision. And yes, it has to be admitted that even if treatment is beneficial, it is possible to make mistakes in the treatment process and make things worse so opting for treatment is not without its risks. Still, there are professional recommendations in favour of it and lots of favourable reports from those who have tried and who have achieved what they regarded as succesful results. I think the risks associated with treatment are both low and manageable and I'm happy to recommend that others try it provided they are prepared to follow the standard recommendations which happen to be remarkably consistent and which don't seem to result in problems.
David Aiken
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