Fig. 2.
Reconstruction of broadband noise stimuli. Temporally orthogonal ripple combinations (TORCs) are specially constructed broadband modulated noise stimuli. A: example of a TORC: In each of 30 different TORCs used for reconstruction, the stimulus consists of the superposition of the envelopes of 6 ripples, all at the same ripple density (0.2, 0.4… 1.2 or 1.4 cyc/octave) and ripple velocities from 4 to 48 and −4 to −48 Hz. Thus the 2-dimensional modulation spectrum (MS) of each TORC is a line at a particular spectral modulation density. B: reconstruction error of MTF (modulation transfer function). The MS of the reconstruction error for all TORCs and from all neurons shows better reconstruction accuracy at lower temporal (top) and spectral modulation frequencies (right). C: reconstruction error for N and T. Normalized reconstruction error as a function of the number of neurons and duration of fit data used for estimation. The reconstruction error converges to lower values for lower temporal and spectral modulations. D: reconstruction error for N and T = inf. Normalized reconstruction error for different temporal and spectral modulations as a function of neuron number after extrapolation to infinite fit data for each neuron.