David J. Atkinson and Andrew A. Catellier

Abstract: This report describes an experiment conducted to measure the intelligibility of selected radio communication systems when those systems are employed in high-background-noise environments experienced by firefighters. The test plan for a Modified Rhyme Test (MRT) is detailed, including requirements for source material preparation and listening test conduct. Finally, the results of the test are presented, along with the data analysis. The results indicate that in some environments analog radios performed better than digital radios, and in some environments no radios performed well. This information should be considered whenever an agency is preparing to purchase and deploy a new communications system.

Keywords: intelligibility; noise; land mobile radio (LMR); Project 25 (P25); vocoder; analog FM; fire service; modified rhyme test (MRT); public safety

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.

Back to Search Results