Figure 8
The utterance “Britta schenkt fünf grüne Ringe.” produced by a female speaker of the airbone database. Note that the beginning is free of speech but contains a lip smack and breath noise. Spectrogram of the (a) signal corrupted by additive white Gaussian noise at 10 dB SNR, (b) clean signal, (c) signal enhanced by the kernel PCA method, and (d) enhanced by kernel PCA and plotted with higher frequency resolution. (e) phase of the noisy signal, (f) phase after kernel PCA. The pattern visible in the phase plot (f) causes the harmonic artifacts in (d).