Like fireflybob, I was flew in the era when we used the one ear uncovered style. In recent years the fashion has changed and now the accepted style is to use the I/C and cover both ears. After some months of experiment with this system, I reverted to the right ear uncovered style for the same reasons that bob has pointed out.
In answer to the question about my hearing tests, yes, the line of crosses stretches neatly across the top of the graph paper, much as it did in 1970 when I had my first test.
I will also point out that I have been very remiss when it comes to the use of ear-defenders during the walk-round. Considering that I have done this more than 15000 times and flown the subsequent flights with the Boeing supplied headset you can see that the manufacturers and sales teams of these headsets have done a good job in persuading pilots that they really do need these extravagant accessories.
If I flew a particularly noisy aircraft, a DC6 perhaps, then maybe I would have a different opinion but for the Boeing/Airbus aircraft that the vast majority of us fly, forget it.
Better send your hard earned money to
RNID.org.uk