Non-locally averaged pruned reassigned spectrograms: a tool for glottal pulse visualization and analysis

Reassigned spectrograms have shown advantages in precise formant measuring and inter-speaker differentiation. However, reassigned spectrograms suffer from their inability to visualize larger amounts of data in an easily comprehensible and reproducible manner. Utilizing the techniques and tools developed by Fulop and Fitz, a variation of the reassigned spectrogram is proposed. Non-locally Averaged Pruned Reassigned Spectrograms (NAPReS) provide a simplified view into the characteristics of a speaker's glottal pulsation patterns throughout the centroid of a vowel through the stacking, summing, and pruning of large numbers of glottal pulses. In this exploratory study, NAPReS has been shown to display a large amount of data in an easily comprehensible and quantifiable manner, while also making the observation of low-amplitude cyclical structures more accessible. NAPReS also allows for alternative formant fitting methods such as Gaussian mixture modeling. In this study, NAPReS with GMM was compared against conventional LPC fitting of formant values and was shown to be more reproducible than conventional LPC fitting in high-noise situations.