Bandwidth extension of audio based on partial loudness criteria

Most modern speech coders operate on a limited bandwidth. This tends to decrease the naturalness of the synthesized audio and often also affects the intelligibility of certain sounds. While a few wideband speech coders have been standardized, implementing them in existing systems would require significant changes to the infrastructure. One solution is to use bandwidth extension techniques that predict the high-frequency band based on low-band features. Problems arise however when the correlation between the low and the high band is insufficient for an adequate representation of the wideband signal. In this paper, we propose a novel source-filter bandwidth extension algorithm that makes use of psychoacoustic concepts to determine the perceptual benefits that a particular audio frame gains from a more exact representation of the high band. Preliminary results indicate that the proposed system performs at a lower average bit rate when compared to other similar algorithms without compromising the audio quality.