Figure 1

With Smt mapping, consecutive tones on the musical scale (illustrated here using a piano keyboard) are assigned to adjacent channels corresponding to either physical electrodes (solid lines) or virtual channels (dotted lines). An array of 22 physical electrodes yields a total of 43 channels. Smt-LF and Smt-MF respectively map the tones from C3 to F6#, and from A4 to D8#, to these channels. Note that the tones C8# to D8# (shaded keys) have been added for illustration purposes only and do not exist on the standard piano keyboard.