Auditory stimuli consisted of 50-ms pure sine wave sounds
(5 ms rise/fall), generated with Audacity software. Tones were delivered binaurally
at ~85 dB SPL using an Etymotic ER-30 system (Etymotic Research,
Inc. United States of America) via plastic tubes and foam earpieces.
The 18-ms delay in the transmission of soundwas compensated for by an
appropriate shift of the trigger signal. The experimental stimulation was
controlled using Psychophysics Toolbox.