When you cut off a human's appendage, the screaming comes from a voice. The voice comes from a sort of... consciousness. Which while we haven't exactly nailed down what makes one up, we are reasonably certain that it involves a nervous system.
https://www.science.org/content/article/plants-communicate-d...
There’s a difference between a creature’s higher level response to a stimulus and just stuff that happens as a direct physical consequence of the stimulus.
It’s the same deal as boiling live lobsters. They aren’t actually screaming, even if you would be. That’s steam escaping. What the plant sound actually is, no clue. But I think the lobster scenario is what was being suggested upthread.