"P.S. How often has anybody done a blind test in which they listened for
days? Let's say 4 switches per trial, 2 days per switch, 20 trials: that's
160 days. Has this ever happened? Ever?"

How often has it been done standing on the right foot while the left hand
is embedded up to the wrist in cheese doodles?

Seriously, the only question is not knowing,ie. blind testing, and all
this other mental tap dancing irrelevant because no restraints otherwise
are required. As mentioned, testing has been done with the only control
being a cloth placed over connections to implement blindness, the results
were obvious.