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Mission Critical Voice Quality of Experience Access Time Measurement Method Addendum



Chelsea Greene, Jesse Frey, Zainab O. Soetan, Jaden Pieper, Silas Thompson


Access time generally describes the time associated with the establishment of a talk path upon user request to speak and has been identified as a key component of quality of experience (QoE) in voice communications. The National Institute of Standards and Technology's (NIST) Public Safety Communications Research (PSCR) division has previously developed an access time measurement method [1]. Improvements were implemented in the access delay measurement method to better handle the idiosyncrasies of the various push-to-talk (PTT) technologies tested. These improvements include a more robust audio alignment procedure, and graceful communications failure detection and handling. This paper covers those improvements to the access delay measurement system, results of testing Project 25 (P25) technologies with and without encryption turned on, as well as some initial Long Term Evolution (LTE) measurements.
NIST Interagency/Internal Report (NISTIR) - 8328
Report Number


Access delay, Articulation Band Correlation Modified Rhyme Test (ABC-MRT), A-weight, Encryption, Key performance indicator (KPI), Land mobile radio (LMR), Latency, Modified Rhyme Test (MRT), Mouth-to-ear (M2E), Packetized, Project 25 (P25), Public Safety, Push-to-talk (PTT), Quality of experience (QoE), Receive, Streaming, Transmit, Vocoder, Voice.


Greene, C. , Frey, J. , Soetan, Z. , Pieper, J. and Thompson, S. (2020), Mission Critical Voice Quality of Experience Access Time Measurement Method Addendum, NIST Interagency/Internal Report (NISTIR), National Institute of Standards and Technology, Gaithersburg, MD, [online], (Accessed May 29, 2024)


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Created December 1, 2020, Updated April 24, 2024