Randomizing positions and identifiers cancels room standing-wave biases in double-blind tests

Evidence

Listeners switched among the loudspeakers at will. Above the screen is a display showing which numerical loudspeaker is active. The number identifiers were randomly changed during the multiple listening sessions, as were the loudspeaker and listener locations to randomize the effects of low-frequency room standing waves (resonances). The loudspeaker locations and music changes were predetermined using random number guided sequences to avoid experimenter manipulation of results—this is the “double” part of double blind. — Toole, Floyd E, Sound reproduction- the acoustics and…, 148

Categorization

• XREF: The randomization of listener/loudspeaker positions to defeat room modes is a clever experimental technique worth emulating. — connects to: Bird augury works as a randomization device countering cognitive and copying biases — Joseph Henrich, The Secret of Our Success: How Culture…, 347