Host laboratory functions for the DoD 2400 bps vocoder selection process

In order for a test method to yield meaningful results the equipment and procedures used to collect and format data for that test must be accurate and consistent. A laboratory evaluating narrowband digital voice coders must be prepared to generate data for a variety of test methods across numerous voice systems without introducing extraneous variability. This paper describes the functions of the host laboratory for the Department of Defense (DoD) 2400 bps vocoder selection process. The generation of calibrated, representative audio input material and the collection of processed speech is discussed. The inclusion of calibration and reference speech systems, a channel simulator, and a common testbed interface is presented. The implementation of a communicability test method is described. Strict attention to detail in preparation and procedure allow these methods to be the basis for any voice communication system evaluation and selection process