Wideband coding of speech using a scalable pulse codebook

Recent standardization efforts have provided motivation for research in the area of wideband speech coding (50 Hz to 7 kHz). Both the European Telecommunications Standards Institute (ETSI) in conjunction with the Third Generation Partnership Project (3GPP), and the ITU-T are currently in the process of evaluating candidate algorithms at bit rates from around 12 kbps to 32 kbps. This paper describes a code-excited linear prediction (CELP) technique used in the Motorola candidate algorithm that is scalable to a wide range of bit rates, thereby allowing the use of a ubiquitous speech model. Preliminary subjective test results indicate that the technique provides very high quality speech that meets or exceeds all requirements for both the ETSI/3GPP and ITU-T wideband speech standardization efforts.