Christopher Redding, Nicholas DeMinco , , , , and Jeanne Lindner

Abstract:

This report describes the objective testing of various vocoders, both singly and in different combinations of tandem configurations, to evaluate overall voice quality in an objective manner. The objective test evaluation was performed using a standardized (and patented) objective voice quality estimation algorithm developed by the Institute for Telecommunication Sciences (ITS). This method determines an auditory distance (AD) and converts it to a finite scale that can be related to the mean opinion score (MOS) scale commonly used in subjective voice quality tests. This testing establishes the feasibility (from a voice quality perspective) of using vocoders in a tandem configuration in order to relay voice communications between disparate systems.

Keywords: communications; mean opinion score; vocoder; speech codec; tandem; voice quality of service; objective testing; logistic auditory distance; subjective testing; perceived speech quality

Disclaimer: Certain commercial equipment, components, and software may be identified in this report to specify adequately the technical aspects of the reported results. In no case does such identification imply recommendation or endorsement by the National Telecommunications and Information Administration, nor does it imply that the equipment or software identified is necessarily the best available for the particular application or uses.

For questions or information on this or any other NTIA scientific publication, contact the ITS Publications Office at ITSinfo@ntia.gov or 303-497-3572.

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