The technologies of ISDN teleconferencing, CD-ROM multimedia services, and High Definition Television are creating new opportunities and challenges for the digital coding of wideband audio signals, wideband speech in particular. In the coding of wideband speech, an important point of reference is the CCITT standard for 7 kHz speech at a rate of 64 kbps. Results of recent research are pointing to better capabilities-higher signal bandwidth at 64 kbps, and 7 kHz bandwidth at lower bit rates such as 32 and 16 kbps. The coding of audio with a signal bandwidth of 20 kHz is receiving significant attention due to recent activity in the ISO (International Standards Organization), with a goal of storing a CD-grade monophonic audio channel at a bit rate not exceeding 128 kbps. Prospects for accomplishing this are very good. As a side result, emerging algorithms will offer very attractive options at lower rates such as 96 and 64 kbps. As we address new challenges in wideband speech technology, several strides in coding research are likely to occur. Among these are refinements of existing models for auditory noise-masking, and a unification of linear prediction and frequency-domain coding.
Bibliographic reference. Jayant, N. S. / Johnston, J. D. / Shoham, Y. (1991): "Coding of wideband speech", In EUROSPEECH-1991, 373-379.