Great news. I've been learning about and implementing real-time DSP algorithms for audio enhancement. (Cortex-M7) I started this hoping to make scifi headphone that enhance hearing for normal people with different presets, but realized what I'm essentially building is more like a hearing aid. Didn't even realize the regularly issue. (Although using the article's terminology, could probably already market this as a PSAP and be fine. (?)).
Check out nuraphones; I don't know enough about hearing and audio to know what voodoo they are doing, but as a person with significant hearing loss, the hearing customization they perform during set up allows the device to emit the right frequencies at the right volume that I can hear a significant portion of the left audio channel (which is impressive, given that I am "profoundly deaf" in that ear).
I'm pretty sure That's what 3M Peltor Comtac headsets do, they have microphones on the outside and speakers on the inside, without passing through gunshots or explosions, so you can maintain situational awareness in a combat situation.
