Phase-Continued STFT TSM

Figure 10.18 shows the phase-continued-frames case in which relative phase is not preserved across FFT bins. As a result, the amplitude envelope is not preserved in the time domain within each frame. Figure 10.19 shows the spectrum of the same case, revealing significant distortion products at multiples of the frame rate due to the intra-frame amplitude-envelope distortion, which then ungracefully transitions to the next frame. Note that modulation sidebands corresponding to multiples of the frame rate are common in nonlinearly processed STFTs.

Figure 10.18: Phase-continued vocoder waveforms at 2X expansion.

Figure 10.19: Phase-continued vocoder spectra at 2X expansion.