Figure 1: Stimulus creation by filtering MPS.
From: Rapid tuning shifts in human auditory cortex enhance speech intelligibility
(a) The MPS describes the oscillatory patterns present in a time-frequency representation of sound. Left, the spectrogram of unfiltered speech is shown. Right, the MPS (calculated from a 2D FFT) is shown. Patterns in the spectrogram are reflected as power in temporal or spectral axes of the MPS. Rapid spectral fluctuations (for example, harmonic stacks from pitch, (1)) are represented near the middle/top of the MPS. Rapid temporal fluctuations (for example, plosives, (2)) are represented near the bottom/sides of the MPS. Joint spectral/temporal fluctuations (for example, rising pitch and phoneme changes, (3)) are represented in the upper corners of the MPS. (b) Left column: Filtered speech was created by filtering either spectral (top) or temporal (bottom) regions of the MPS space. MIDDLE column: spectrograms of the resulting filtered speech is shown. Right column: re-calculating the MPS on the filtered speech spectrogram shows that the MPS is now lacking power in the filtered regions.
