Virtual electrode analysis of the ROI.

<p>Normalised response amplitudes for the four AM conditions. For the lines in the left plot, and the points in the right plot, the following colours are used; mixed-width (black); fixed-width 16 ms (red); fixed-width 24 ms (green); fixed-width 32 ms (blue). The amplitude of the FFT spectra are normalised by the amplitude of the 4 Hz component in the ASSR to the mixed-width stimuli, the 4 Hz energy in the stimulus waveforms are normalised by the 4 Hz energy in the mixed-width waveform. The normalised energy at 4 Hz in the four stimulus waveforms are; fixed-width 16 ms, 0.68; fixed-width 24 ms, 1.01; fixed-width 32 ms, 1.32; mixed-width, 1. The normalised amplitude at 4 Hz in the FFT spectra of the four responses are; fixed-width 16 ms, 0.88; fixed-width 24 ms, 1.02; fixed-width 32 ms, 0.99; mixed-width, 1. When the response amplitude is plotted against the energy in the waveform, right plot, the solid black line shows what would be predicted if there was a linear relationship between the 4 Hz component in the ASSR and the stimulus waveform. The dashed black line is the observed relationship for the three fixed-width AM conditions.