A new very low bit rate wideband speech coder with a sinusoidal highband model
Julien Epps, W.H. Holmes · 2002
A great deal of research attention has been directed towards quality improvement in narrowband speech coding. Although wideband speech coders are capable of achieving higher quality speech, at only slightly greater bit rates. This paper presents a new wideband speech coder that augments any existing narrowband coder with a very small bit stream that represents the highband speech. The highband excitation is synthesized using a sinusoidal model whose parameters are determined directly from the decoded narrowband speech. The highband spectral envelope and gain are vector quantized in a manner which exploits information from the decoded narrowband speech. Thus, the overall bit rate of the wideband coder is around 150 bit/s greater than that of the embedded narrowband coder. In subjective tests, speech which was coded by the new wideband coder was preferred to the narrowband speech.