Auditory Motion
The auditory stimulus consisted of an amplitude modulated (F c = 20 Hz) broadband white noise sampled at 48 kHz that was created at the beginning of each trial. This noise was divided into 11 segments, one for each of the 11 speakers along the soundbar. Smooth apparent motion was created by playing each speaker in sequence using a crossfade and by applying a sine window to the onset and offset of each noise segment. To eliminate loudness variations between individual speakers, the sound pressure level of each speaker was tested and calibrated to ensure equal loudness of (~75 dBA), as measured at a distance of 1 m with a sound pressure meter. To prevent subjects from using distance and location cues as a basis for velocity judgements, the start- and end-points of the sounds were randomly jittered by ±15° (3 speaker intervals, see Freeman et al, 2014). All stimuli were generated on a MacPro (Apple Inc.) running MATLAB (R2016b, The MathWorks, Inc., Natick, Massachusetts, United States) and Psychophysics Toolbox extensions35,36.