Combining frontend-based memory with MFCC features for Bandwidth Extension of narrowband speech

In this paper, we continue our previous work on improving Band-width Extension (BWE) of narrowband speech. We have shown that including memory into the parametrization frontend (through delta features) results in higher highband certainty irrespective of feature type, with MFCCs exhibiting higher correlation, in general, between both bands, reaching twice that using LSFs. By incorpo-rating memory into the frontend of a conventional LP-based BWE system, we were able to translate the higher correlation due to mem-ory into BWE performance improvement. Using high-resolution inverse DCT, we also achieved high quality speech reconstruction from MFCCs, thus enabling MFCC-based BWE with improved performance compared to conventional static LP-based BWE. We continue this work by incorporating the superior correlation prop-erties of frontend memory into our MFCC-based BWE system. Log-Spectral Distortion as well as the more perceptually-correlated Itakura-based measures show that incorporating memory into our MFCC-based BWE system results in BWE performance superior to that of our dynamic LP-based BWE system. Index Terms — Bandwidth extension, memory inclusion, high-resolution IDCT, highband certainty, mutual informatio