Subject Keywords: Analog, Audio, A-weight, Communications, Direct mode, Distortion, Frequency, Frequency slope fit (FSF), Key performance indicator (KPI), Land mobile radio (LMR), Mission Critical Push-to-Talk (MCPTT), Mission critical voice (MCV), Mouth-to-ear (M2E), Optimal volume plateau identification algorithm (OVPIA), Project 25 (P25), Plateau, Public safety, Push-to-talk (PTT), Quality of experience (QoE), System under test (SUT), Transmit volume optimization (TVO), Volume.