Artificial Bandwidth Extension (ABE) has been introduced to improve perceived speech quality and intelligibility of narrow-band telephone speech. Most of the existing algorithms divided ABE into 2 sub-problems, namely extension of the excitation signal and that of the spectral envelope. In this paper, we propose a new method for spectral envelope extension based on REgularized piecewise linear mapping with DIscriminative region weighting And Longspan features (REDIAL). REDIAL is a revised version of SPLICE, a well-known method for speech enhancement. In REDIAL, however, discriminative model is introduced for space division step of the original SPLICE. The proposed REDIAL-based method approximates non-linear transformation from narrowband features to their wideband counterpart by a summation of piecewise linear transformations. The proposed method was compared with the widely used GMM-based method, through objective and subjective evaluations in both speaker-dependent and speaker-independent conditions. Both evaluations showed that the proposed method significantly outperforms the conventional GMM-based method.
Bibliographic reference. Duy, Nguyen Duc / Suzuki, Masayuki / Minematsu, Nobuaki / Hirose, Keikichi (2013): "Artificial bandwidth extension based on regularized piecewise linear mapping with discriminative region weighting and long-Span features", In INTERSPEECH-2013, 3453-3457.