Ok, I reformulate. IF there are 5 rifle shots on the recording, it have to be McLain. The probability for the 5 detected rifle shots being random noise is P = 1/100 000.
That give you three ways forward:
1. Show that the data for the mike being somewhere else is P > 1/100 000.
2. Show that the probability isn’t that low for something else than 5 shots on the recording.
3. Both.
Which is it?
What is your source for these numbers?
The HSCA acoustic report from Weiss and Aschkenasy concludes that:
It is conceivable that a sequence of impulse sounds, derived from nongunshot sources, was generated with time spacings that, by chance, corresponded within one one-thousandth of a second to those of echoes of a gunshot fired from the grassy knoll. However, the probability of such a chance occurrence is about 5 percent.
This is p < 0.05, not p < 0.00001 as you are claiming. Furthermore, they concluded that there were 4 shots, not 5 as you are claiming.
If you are taking the numbers from Donald B. Thomas, he concludes:
A conservative estimate of the true value of the probability that the putative Grassy Knoll shot is attributable to random noise is no greater than 0.037.
He is saying there were 5 shots with p < 0.037. This is still 3700 times larger than the p-value you cite.