Fig 12. Transposing low-frequency tones into high-frequency regions of the cochlea.

(A) An example of three sparse coefficient vectors, h, for the three frequencies f₀ = 229 Hz, 249 Hz, and 269.7 Hz. The resulting h vectors have the same nonzero indices, i.e., these stimuli cannot be differentiated based on their sparse representations. (B) The pdfs of the three TTs are noisy and inconclusive, as expected. (C) Predictions of 100 epochs; only the 1^st peak in the pdf is considered. There are two distinct types of stimuli: (i) pure tones (blue), and (ii) TTs (red). Both stimuli are simulated with incremental fundamental frequencies of f₀ ∈ [100 Hz, 500 Hz]. Each stimulus is normalized relative to the fundamental f₀. The model could estimate the f₀ of the pure tones with a high degree of accuracy but could not predict those of the TTs at all (compare with [13]).