Codebook-based Bandwidth Extension with Side-Information

With the Bandwidth Extension (BWE) techniques it is possible to enhance the bandwidth of limited speech signals and provide backward compatibility with respect to the communication networks. Artificial Bandwidth Extension (ABWE) uses correlations between the low and the high frequency ranges, to predict a wideband signal outgoing from a narrowband signal [1, 2]. The advantage of the ABWE technique is that only the receiver has to be adapted. However, ABWE only provides good quality if the correlations between the low and high frequencies are large. Especially in noisy scenarios like hands-free car communication the correlation decreases and with it the quality of the BWE. Therefore, the speech quality of ABWE is clearly affected in comparison with a wideband speech transmission [1].