Would it be possible to have the uploader check the audio content of files to meet certain thresholds in order to apply these tags?

I think there's a lot of posts with sound_warning that don't really need it, while others have the opposite issue.
To go through them all and check is something that could easily be done by a bot very quickly, but is a tremendous chore for humans.
Aside from standard peak and RMS values, there are some other more sophisticated weightings that could be applied depending on how you'd want it to function.
My reference would be the free Orban Loudness Meter, though I don't know if it could be integrated and/or run in offline mode rather than live to process files quickly.
CBS, ITU BS.1770 Momentary, Short-Term and Integrated, VU, PPM and Reconstructed Peaks are all measured in Orban.
https://www.orban.com/meter

To take 2 example posts, we have this one without a sound_warning tag: https://e621.net/posts/1874774
You've got maybe -6dBFS peaks and maybe -18 more averaged

Then this post, that does have a sound_warning tag: https://e621.net/posts/3041627
This one doesn't even show up on the scale unless I boost the signal massively. (The scales start at -30 and -41)
Not to mention the very slow crescendo in that post, the sound levels don't hit you unexpectedly or anything.

Maybe this is more processing than e6 would consider doing...

The sound_warning overuse continues to pervade the site.
My recommendation at this time is to change the tag-type of the sound tag to an artist tag like sound_warning, as I'm sure the main reason people use it is due to that characteristic

Maybe alias sound_warning to loud_warning? That way, its purpose is much clearer, people won't mistake it for meaning "this post has sound"

It's a problem right now, it's been a problem in the past, and from the looks of things it will continue to be a problem in the future. At this point I've simply stopped caring and accepted every single one of my posts is gonna be erroneously tagged with it no matter what

See topic #41399 for another recent discussion of the issue, and the comment I made on topic #42142 for a possible solution I talked about back in the day
although at this point if someone steps up and suggests to just completely invalidate sound_warning due to how problematic it is, I'm in full support

mabit said:
See topic #41399 for another recent discussion of the issue, and the comment I made on topic #42142 for a possible solution I talked about back in the day

If you're talking about this:

mabit said:
A "Warning" category in general would be really good actually. sound_warning and conditional_dnp would fit much better there instead of being awkwardly crammed in the artist section for visibility

We also already treat the "contentious content" tags/ones in the global blacklist a bit differently than other tags in the way that you're required to include them. Having all of those in a Warning category makes a lot of sense

I've been told by staff before that creating another category "isn't happening" for any reason, apparently there's been an internal push to get new tagging categories but nothing has come of it. I think a Warning category would make a lot of sense, although it'd have to be very visible with some kind of alt-text when you hover over it explaining what the category is for. Unfortunately we're probably not getting a new category for a long time or until the staff can figure out what to do about whatever thing they're internally pushing for.

A new category is unlikely to be created even though there have been calls for it constantly (modellers category, music/voice actor category, warning category) and the suggestions have been brushed off due to what I believe is technical debt that makes adding more categories very difficult or requires workarounds (like with the newest category lore requiring _(lore) at the end of the tag)
I believe there's also an unused category or two lying around.

I may be incorrect about everything said above though, this is what i recalled from memory

If the category stuff has been shown to be off of the table already then there's no use talking about here anymore, it would be way more useful to keep talking about how sound_warning is a problem tag that's misunderstood by both users and staff like shown in that other topic

It hasn't gotten any better in the months since it was last brought up, there was somewhat of an effort to clean it up but the problem just came back exactly as before because not much was done about it

Something needs to happen with it. Tagging loud, especially startling sounds, is necessary. Making 'loud_warning' and 'screamer' tags might curb it while aliasing 'sound_warning' to 'sound' maybe? For what it's worth, keeping 'sound' in the artist/warning position isn't a bad idea- give people a heads up to mute their speakers before accidentally blasting wet slaps to the world.

Yeah, I'm going to be honest, sound_warning has gone from a potentially useful tag to probably being one of the most useless tags on the site because of all of the mistagging.

Really what should happen is that it should me aliased away to something that makes it obvious that it's meant for lound noises/earrape only. I would honestly just suggest unaliasing sound_warning -> ear_rape, moving all of its aliases over, and then invalidating sound_warning to prevent future mistags