Many tests are not needed to disprove a claim, just one if the test matches the conditions in the claim and given how broad those claims often are in audio, or how specific they are, it is easy to replicate the conditions purported in the claim, right down to the specific test subject.
The great thing about blind testing is it isolates the auditory system as the exclusive "test". Really, that is all it does. It ensures that only the "ears" are used in the testing.