The only real constraint now is volume - there's still a hard db limit of 111 db because of the technicalities of medical device categorization. Software and hardware patents are entwined with the medical device nonsense and the hearing cartel is incredibly litigious. They make FAANG look like playground bullies if they feel their territory is being infringed on, and have an absurd breadth and depth of patents covering every possible iteration and permutation of audio technology they can possibly get away with.