Table 1. Cue properties in BCI experimental round.

Direction	Nr	Lower bound (Hz)	Upper bound (Hz)	Tone (Hz)
Left	7	320	2500	440 (a)
Front-left	8	416	3250	494 (b)
Front	1	540	4225	554 (cis)
Front-right	2	703	5493	622 (dis)
Right	3	914	7140	699 (f)

Nr refers to the speakers labels given in Figure 1. Lower- and Upper bound are the boundary frequencies for the band pass filter that is applied to the white noise. Tone is the fundamental frequency of the tone overlay. Seven harmonics were used, with decaying amplitude. Tone frequencies are chosen to have a full note in between adjacent stimuli.