I listened to the recording in the article, and it sounds like a human. Further, it sounds like the same human. And I found myself reading the emotional message behind the sounds. So...yeah, it's an interesting theory, but I think it's more likely a prank or someone making a point.

There's a point in the MP3 that sounds possibly non-human at 0:18 to 0:19. The pitch goes quite high in a way that sounds artificial.

But overall I agree that it sounds very human. For example, the grunt at 0:13 doesn't sound like random noise at all, it could easily be a sound effect in a movie or game.

Another way to think about it: there are a lot of planes and different ways the PA system could go wrong. You’re much less likely to read an article about a plane being ‘haunted’ by a strange clicking or buzzing or humming or white noise sound.

But why would I think that way? I listened to the recording, it sounds human to me. Why would I need to crunch further data?

I think you’re trying to decide if it’s a prank or not. And (I assume) you care about trying to come to conclusions that are likely correct. Therefore I think you should care about things that would lead you to incorrect conclusions.

Suppose the two possibilities are ‘prank made from human’s voice’ and ‘weird electromechanical phenomenon’. The logic I believe you’ve implicitly applied is that most electromechanical phenomena do not sound human and therefore this human-like sound is likely human. However I put it to you that this logic is flawed because you have not heard a randomly sampled electromechanical phenomenon but rather a sound that was sufficiently human-like to warrant an article about hauntings so thinking about the ordinary distribution of electromechanical phenomena is misleading.

Furthermore I think that you’re assigning relativity equal weight to the two possibilities of a human prankster and any kind of PA system fault when I would argue that the latter is much more common. That is, I think you’re answering a question like ‘we flipped a coin and if it came up heads, we made silly noises into a dictaphone and if it came up tails we tortured the device in some way while it was recording. We’ll play the sound and you can guess which it was’ whereas I think the answer in this case hinges a lot more on the equivalent of the coin-flipping process (eg what if you needed 10 heads in a row for the first choice? What about 15? 20?)

One can formalise this too. I’ve tried to come up with some priors that illustrate the point and which I think are reasonably generous towards your conclusion.

  Say H = some human pranking a flight with silly noises,
      M = some mechanical failure in the PA system,
      Mh = human-sounding mechanical failure
      Mm = mechanical-sounding mechanical failure
      S = human-like sounds
  
  And let’s invent some numbers for a random flight:
  P(H) = 1e-6 (feels too big to me)
  P(M) = 1e-3 (feels a bit small to me)
  P(Mm | M) = 0.995 (I.e. 99.5% of mechanical sounds sound mechanical)
  P(Mh | M) = 0.005
  
  We read an article about S happening so we now wonder:
  P(H | S). Apply Bayes theorem:
    = P(H) P(S | H) / P(S)
    = P(H) * 1 / P(S), and in our model
    = 1e-6 / P(S).
  
  Now what is P(S)? We can calculate in our model (assuming we’re describing all possible causes and for simplicity ignoring a flight with a human-sounding mechanical failure and a prankster).
  P(S) = P(H) + P(Mh)
       = P(H) + P(Mh | M) * P(M)
       = 1e-6 + 0.005 * 1e-3
       = 6e-6

  And we can plug that back into the equation above:
  P( H | S ) = 1/6

You can fiddle around with the priors and get a feel for how the affect the results but the point I want to make is that it can be true that electromechanical sounds are very rarely human-sounding and still be likely that the sounds in this case are likely electromechanical. I believe that your argument was based on the incorrect logic I described at the start of this comment and not because you had strong priors that the very unlikely event of a human prankster was more likely than the combination of the unlikely events of a faulty PA system and a fault making humanoid sounds.

Your post is an example of forced rationality.

You're ignoring the fact that it's not just one production. I would consider your position if there was one continuous production with small to no variations.

Why are you ignoring the following?

- the sounds have the length of a yell or a moan.

- the silence between them is not fixed or related to any other sound that we can hear on the plane.

- there are no artifacts, except the weird pitch going up artificially in one of them, which might point to a prerecorded and manipulated sound

- if this was a electromechanical issue, it would have to mimic a significant part of the human anatomy, including a tongue (there are a few productions that sound like the throat is constricted and the tongue is rolling slightly).

Sure, a random electromechanical issue could have these characteristics, but isn't that extremely unlikely? You would expect other noises, not just the vocal-like sound.

Also I'm pretty sure I heard the sound of clearing the throat and spitting in the recording. Too many distinct categories of human-sounding sounds to be random electro mechanical or electromagnetic phenomena.

That's because a strange clicking or buzzing sound is much less likely to be a human voice.

There was a post on Reddit, I think, that explained that there were ports in the luggage bins every so many seats that were for for medical comms to run on. Someone plugging something into this port could play whatever they wanted from a computer. It's probably the same person doing the same joke over and over.

The only problem for them is that AA could cross reference the travelers on those flights to figure out who it was, if it was a passenger using these ports to prank.