They're working on it, but not yet. I don't understand in 2020 hi tech era, we will permanently be on the moon in 4 years etc., but, this tech doesn't exist, yet.
It will get more attention as Gen X gets to the "Wha!? Stop MUMBLING!" stage of life. And, a continuing acceptance that hearing is an easily lost and irreplaceable sense. Which attitude has changed in just my lifetime.
It's also two problems at once, too.
One is the decibel volume, the other is the intensity of the sound (which is an over-pressure). That latter is why 5.56nato is actually more damaging than .44magnum (understanding that both cause damage).
Which is not much helped by organizations like OSHA, mostly focusing on long-term, eight-hour work shift, exposures, and setting limits by fiat, rather than by science. (This is where we get the 140dB = hearing "safe" thing--that's an industrial exposure rule, not a medical one.)
What's needed, probably, is a valved system that can respond to over-pressure, as well as a decibel-gauged limit. All in a package that can be conveniently be stuck in human ears over a wide range of body measurements.
Flying to the moon is relatively easy, it's fifty-year old tech at this point.