FWIW readers of Floyd Toole's 'Sound Reproduction' should already have an excellent grasp on this subject - it is a truly comprehensive study on how we perceive sound!
The adaptability of human hearing has already been studied(Floyd even did so in his Ph.D experiments), so it should be no surprise that the listeners adapted to hearing with the silicone pieces.
The Times' comments section suggest some are looking to this for potential treatment of hearing loss. Changing the shape of the ear cannot compensate for presbycusis. As always, we need to respect and care for our hearing. We have many charts explaining safe listening levels, and the need for hearing protection when those levels are exceeded.
I appreciate your adding the AVS link - Floyd continues to wave the flag that says we all need to expect better standardization in our recordings. We won't improve how we hear by changing the shape of our ears, at least until what we are hearing has been standardized!
From Production to Reproduction in all the various forms we may listen, there needs to be a soundtrack mastered to account for that. And the one that does exist (X-curve) is not only fundamentally flawed, it also is not consistently applied in Commercial Cinemas, nor should it have ever been applied to Home Theaters as Floyd detailed in his
Measurement and Calibration of Sound Reproducing Systems.
