Objective Analysis of the Effect of Memory Inclusion on Bandwidth Extension of Narrowband Speech

For the purpose of improving Bandwidth Extension (BWE) of narrowband speech, we continue our recent work on the positive effect of exploiting the temporal correlation of speech on the dependence between speech frequency bands. We have shown that such memory inclusion into MFCC speech parametrization translates into higher highband certainty. In the work presented herein, we employ VQ to estimate highband discrete entropies, thus refining our analysis of the effect of memory inclusion on increasing highband certainty. Moreover, we extend our previous analysis to LSF parameters. We further construct a BWE system that exploits our memory inclusion technique, thus translating highband certainty gains into practical BWE performance improvement as measured by the objective quality of reconstructed speech. Results show that memory inclusion decreases the log-Spectral Distortion of the extended highband speech by as much as 1 dB corresponding to more than 14% relative. Index Terms: Bandwidth Extension, Mutual Information.