Artificial bandwidth extension of narrow-band speech signals via high-band energy estimation

In this paper, we describe a novel method of tackling the problem of artificially extending the bandwidth of a narrow-band speech signal. For a given narrow-band signal, we first estimate the energy in the high-band. The high-band energy is then used to select a suitable high-band spectral envelope shape that is consistent with the estimated high-band energy while simultaneously ensuring that the resulting wide-band spectral envelope is continuous at the boundary between narrow-band and high-band. The scalar high-band energy parameter thus effectively controls the artificial information added to the high-band of the bandwidth extended output speech signal. Artifacts in the output speech are minimized by adapting the high-band energy parameter appropriately. Formal subjective listening tests show that the bandwidth extended speech output generated by the described method outscores the input narrow-band speech by 0.25 MOS.