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The trigger for the Silencium hat says
answer a question that has never been commented on; your answer gets no comments and scores 7+
Which makes it sound like the question can get comments on it after I post an answer. However the short description says
answer +7 with no comments on Q or A
Which seems to imply that neither the answer nor the question can have any comments.
So does the answer have to reach +7 with no comments on both my answer and the question? What about other answers?
With the help of this SEDE query I think I can probably give a definitive answer to this.
For example, this answer on Stack Overflow
but its owner does not have the Silencium hat. So that means the short description is correct.
Note that the hat is identical to the "007" hat from the 2015 edition. I found this chat message by Logan M:
I'm now almost positive the requirement is 7 score with no comments on the question or answer, possibly <30 minutes required as well.
and the description in Winter Bash 2015 Secret Hats does not imply that the question can receive comments after you post your answer (and before you get the hat).
What about other answers?
I can answer this part from personal experience; I got my Silencium hat for this answer while there were comments on Journeyman Geek's answer (long before my answer reached +7). So the other answers aren't checked for comments.
