Fig. 1.

Experimental design and setup. (A) Overview of our “substitution” approach, including the original sound-based versions of the illusions we explore here (Top) and their silence-based counterparts (Bottom), created by substituting silences for sounds. (B) Setup and immersion procedure for Experiments 1 to 7. Subjects wore headphones and underwent a check exploiting the fact that antiphase tones sound different on headphones than loudspeakers (25). In all experiments, an ambient noise played until subjects were fully immersed in the soundscape. Periods of silence were introduced during individual trials by briefly cutting out the ambient noise. (C) Ambient noises used for Experiments 1 and 2.