Combination of LSF and pole based parameter interpolation for model-based diphone concatenation

For speech generation using small databases, spectral smoothing at the unit joints is necessary and can be realized by an interpolation of model parameters. For that purpose, the LSF are the best choice from the conventional parameter descriptions. This contribution shows how LSF interpolations can be improved using poles as parameters. The problem of the pole assignment between the two pole configurations at the unit joints is solved by pole tracking of an LSF transition. An inspection of the assignments determined by LSF transitions reveals unfavorable cases which can be corrected. A comparison between the LSF and the pole based interpolations shows that the LSF interpolations can be improved by the corrected pole assignments and by the trajectories of the poles. The investigations are performed using a diphone database which is analyzed by an extended LPC model in lattice structure including vocal tract losses.