A Comparative Study on Excitation Extension Algorithms for Artificial Bandwidth Extension

F. Schäfer, T.V. Pham, G. Kubin (Austria) and T.T. Chien (Vietnam)


artificial bandwidth extension, excitation extension, source-filter model, objective speech quality measures


The most common approach for artificial bandwidth extension is based on the source-filter model such that the estimation of missing signal components is done in two stages: excitation extension and spectral envelope exten sion. In this paper we address an objective comparison be tween different excitation extension algorithms while the wideband spectral envelope is assumed to be known pri orly. A variety of methods have been implemented and subjected to several objective quality measures. All meth ods are tested with the NTIMIT corpus and the bandpass filtered TIMIT corpus. The results show that: 1) different extension methods provide roughly the same speech qual ity which implicitly means the choice of the method can be made on account of the efficient implementation; 2) under estimation of the extended components is to be preferred over an overestimation of these; 3) the PESQ-MOS is a most suitable objective measure for evaluating bandwidth extended speech signal.

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