Slope comparison of OpenBCI and Brain Products at baseline.

A) Baseline raw Power Spectral Density (PSD) for OpenBCI (red trace) and Brain Products (blue trace) averaged across 11 subjects (thickness of the trace indicates the standard error of PSD across subjects at each frequency). Dotted lines show PSD of shorted electrodes for instrument noise measurement. C) Slope of the PSD vs Frequency plot averaged across all subjects for two frequency ranges (16–34 Hz and 54–88 Hz) for OpenBCI (red) and Brain Products (blue). The error bars indicate the standard error. B, D) Same as A, C, but after selectively attenuating the mains/line noise component (see Methods for details).