Physical headphone testing cannot be fully blinded because listeners feel weight and fit

Evidence

Conducting comparative blind listening tests on headphones presents several challenges not encountered when testing loudspeakers. There is no equivalent headphone version of the automated speaker shuffler that allows fast A/B/C/D blind comparisons that also removes positional biases from the test (see Figure 10.11). Instead, a test administrator must stand behind the listener and manually swap the headphones on demand. The listener must make fine adjustments to the positioning of the headphone to ensure it is properly seated and sealed. This interaction can inevitably lead to the identification of the headphone either by its weight, clamping force, comfort and feel of the cushions on the ears before the listener has even seen or heard it. — Toole, Floyd E, Sound reproduction- the acoustics and…, 1775