Further, from the link that you provided!
"4.1 Test Conditions
The shot sequence was unknown to both of the observers. Because repeats of certain shots were requested during the sequence, I was also uncertain - despite knowing the planned sequence.
We requested three motorcycles to be running during the test to provide some background noise that would approximate the original listening conditions in Dealey Plaza. Unfortunately, these newer motorcycles were not very noisy, but the shots were so loud that any reasonable level of background noise would have been low in comparison with the shots themselves. Our listening conditions were, therefore, essentially representative of those at the time of the assassination, except for our being able to hear some very-low-level, long-delay echoes that originally might have been inaudible.
Our observers did know that there were only two possible locations for the marksman, whereas there was considerably more uncertainty on this issue at the time or the assassination.
Signal uncertainty of this kind generally does not seriously degrade the accuracy or Judgments, but it does depend on the number or potential alternatives. In this case, as we shall see, the localization reports made by the trained listeners were, for the most part, or general areas, rather than specific windows or a building. The total number or potential locations was not, therefore, large and, thus, was likely to be representative of localization responses given at the time of the assassination.
4.2 Analysis of Observers’ Localization Responses I
The descriptive comments made by the observers are difficult to compare with any degree of precision. However, there was clear agreement in their reports with respect to the apparent loudness or the sounds and echoes and the apparent size of the acoustic image. After each test shot, we asked the two observers to guess whether the shot was fired from the TSBD or the knoll, independent of what the apparent locus might be. Table IV is an analysis of this forced-choice data."
[qimg]https://www.dropbox.com/s/3u5lymw44dqj5hc/TableIV.png?raw=1[/qimg]
Now, if am understanding this table correctly, three sequences of shots were fired randomly from either the TSBD or the Grassy Knoll. The test subjects were told only to choose between TSBD or Grassy Knoll as the source of each shot
In the first sequence
Dr Wightman correctly identified the locations of all 12 shots
Dr. McFadden correctly identified 11 out of 12 locations... he got one wrong
In the second sequence
Dr Wightman correctly identified 11 out of 15 locations... he got four wrong
Dr. McFadden correctly identified 14 out of 15 locations... he got one wrong
In the third sequence
Dr Wightman correctly identified the 19 out of 25 locations... he got six wrong
Dr. McFadden correctly identified 23 out of 25 locations... he got two wrong
So, out of 57 shots altogether, Dr, Wightman misidentified the location of the shots ten times (17.5% fail rate) and Dr. McFadden misidentified the locations of the shot 4 times (7% fail rate). Under ideal conditions, knowing that the test shots were only coming from either the 6th floor of the TSBD or the Grassy knoll, these two expert witnesses, still managed to get it wrong 14 times between them.
Well, I've just done that for him... and guess what? It doesn't support your claim at all. Do you still stand by your claim that a shot from the TSBD could not be mistaken for a shot from the Grassy Knoll?