So, we see a sonic crack that made it such that we couldn’t hear the “boom”. This shot was not from the ESU officer. It was from “behind” the Podium, so, most likely, the South Barn.
Shots 9 and 10 were obviously not both from the ESU officer. (I’m very sorry that my initial analysis incorrectly said they were. I was wrong!) This is kind of old news at this point, so can we please accept this and move on?
For those who remain unconvinced that the police cruiser audio has been tampered with even though there is no variation in how shots 1-8 were recorded, here is a simple illustration. There is a broad spectrum of colored noise (rolling off towards high frequencies) present throughout the recording. Here is the frequency spectrum for a period between shots 3 and 4 for track 1. It is nothing but noise, and rolls off significantly around 800 Hz, but noise is being picked up to over 13,000 Hz, and there are three bands of higher energy at 4900, 8100, and 11,800 Hz.
These peaks are visible as horizontal brighter stripes in the spectrogram view of the same region of the recording. Note also that there is noise energy all the way up to 13,000 Hz (anywhere it is not black).
There is no reason why this background noise would ever not be there in a real recording. Guess where it drops out? At the positions of shots 1-8, but not 9, which I assume no one had any reason to tamper with. Here is the spectrogram of all three channels and the first nine shots:
See where the higher frequency noise drops out at the locations of shots 1-8 (more visible in channels 1 and 3, where the shots signals were weaker and so pasting them disturbed the recording more)? (Also, it is not as prominent at the locations of 6-8 as those were pasted in slight overlapping fashion) Those black holes where noise is missing should not be there. Look at shot 9 at 5:03–the noise is still there (as it is on shot 10 and in other recordings). But in cutting and pasting for shots 1-8, they wrote over the telltale background noise spectrum, creating “black holes” in the spectrogram where noise should be.
Here is another frequency plot at the location of shot 2 in track 1. The background noise above 2000 Hz has largely been “disappeared.”
In the physical world, when different signals arrive at a microphone, they superimpose, not kill each other. The inside of that cop car does not represent the physical world.
No Greg. That is nonsense. The shot signals on tracks 1 and 3 never reached half of full amplitude, and I see no evidence of AGC. Here is a much more energetic sound at two seconds that actually maxed the amps, and there is no noise dropout.
I know you want desperately to believe in this source that confirms what you want it to confirm, but it is not right. And if it is not right, it proves a coverup. That is why it is not “nothing” and I am making a big deal.
In your previous post you shared your Excel sheet as follows:
Which according to my analysis turned out to be false. Do you agree with my analysis? If so, maybe you should retract your Excel sheet to avoid any confusion or at least admit you made a mistake? As you know we are trying to find out the truth and if you post misleading information, it only hinders others to get to the truth.
If you feel that your numbers are correct, please evaluate how?
With a view to this post, could you take a horizontal photograph of the wires running from the wooden electric pole (with a white transformer on it) to barn #16 and #15, approximately from Trump’s position?
Okay, @offtheback. You are correct about that, and I stand corrected. I just took another look at the dashcam video, and the shots do seem quiet enough that they should not have triggered AGC. However, something clearly caused that spectral suppression. And why is it less pronounced on channel 2, the one with more background noise?
So, what is your theory for how the doctored video came into being? What I mean is, what do you think the original cruiser audio sounded like, and what was the intended goal of the engineer or team of engineers that tampered with the tracks? Were they trying to fool us into thinking that there was only one shooter that day, etc. ?
All I know is that for the longest we had no police video or audio, and then we got a dump of a bunch of things after a long delay, and all of them had the audio masked but this one. Why? Was it too hard to do this manipulation to 12 sources? Are they waiting for us to go through this one and then they will do a better job on the others and release them in a few months?
Honestly, I think the original audio was more like the other sources around the building. I don’t know why we should expect different. The shot timing was off slightly between the two shot groups, and they didn’t have the same audio signature. Since this was a controlled stationary environment close to the shooter with no crowd around screaming, if the timing didn’t match the podium, and the signatures weren’t all similar, that would be a huge problem.
So I think they released it to support the single shooter narrative, absolutely. They should have put in a bit more work though. No other source has the shots all sounding exactly the same. At the very least they are different bullets, slightly different aim, gun barrel heating up, so many reasons they should NOT match each other.
Maybe it is totally bad/stupid question, but I’d like to ask anyway.
How the window glass (of patroler car) attenuated the shots, what could be the filter delay time? I assume at molecular level the “clock” frequency is at THz range. But the spectral frequencies are proportional to the clock frequency. So the 4 kHz cutoff should belong to enormous delay time. So what’s going on?
@greg_n (and @sonjax6), I’m not a mathematician, but I think there may be a problem with the equation. This is just based on your image, Greg. It calculates the time of the crack as 38 ms, moving perpendicular to the path of the bullet. However, I found this equation, according to which the shockwave moves perpendicular to the Mach angle. In other words, not from “B”, but from a distance slightly farther back towards the shooter.
The nice thing is whatever filter function the window provides, it is a) constant for all shots, and b) for noise in the cabin and amps/ADCs, not applicable.
The only other thing I considered was that the audio codec was selectively and spectrally compressing out noise during higher amplitude excursions. But I found plenty of other examples (see all the sounds just before 6 minutes) where sounds were even louder and the higher-frequency, lower amplitude signal was retained. And to a large extent this isn’t even visible in channel 2, which had a higher shot signal. So no AGC, no strict data compression seem to be applicable to this case.
A shorter barrel length (16 inches compared to 20 inches) reduces the muzzle velocity. So while a 20-inch barrel might shoot 5.56 ammo at 3270 fps, the same ammo fired from a 16-inch barrel will be something like 200-300 fps slower. Also, different bullet manufacturers will have a range of muzzle velocities. (E.g., 55-grain from 20-inch barrel can vary from 3175 fps to 3426 fps, according to 5.56 Ballistics Charts From All Major Ammo Makers)
The sound travels perpendicular to the shock wave, that is correct. This is considered on triangle 123, were on 2 it has a right angle, therefore the line 23(Mach cone) travels perpendicular to the sound speed velocity vector (12).
Hi @offtheback.
Could it be that the shoot from 9 and 10 were further form the cruizer therefore the higher frequencies were attenuated?
I also don’t know if the camera microphone is inside the car.
Can you compare the frequency spectrum of the other sources? It would make sense that the higher frequencies of shoots 1-8 were more attenuated than shoots 1-8 from other sources.
I think offtheback was using the audio track that comes from a mic that we know is inside the car because we can hear the A/C running. When we’re sitting in the cabin and hear gunshots, yeah, they will be muffled, but that won’t mute the high frequency stuff we were already recording.
@vt1, what @brian60221 said. We are looking for all of the ambient noise in the cabin and asking where did it go? For instance, here is the signal at a random place in the space between shots 3 and 4, and I have filtered out everything below 8 kHz so we can focus on the high-frequency noise:
Now here is a plot during shot 6. For over 1,700 audio samples, there is no high frequency noise recorded at all. At all. This is beyond unusual, it is unexplainable.
