Artificial bandwidth expansion method to improve intelligibility and quality of AMR-coded narrowband speech

Speech quality suffers from the limited bandwidth of cellular telephone systems, making it sound muffled. In addition, intelligibility is degraded due to missing higher frequency components. The proposed enhancement system is designed to improve both intelligibility and quality of narrowband speech by expanding the bandwidth and creating new spectral components to high frequencies in the receiving end of the transmission link. The algorithm can be used together with conventional narrowband speech codecs and it is designed to be robust in different noise conditions. In addition, the computational load of the algorithm is reasonable.