Figure 2. A suggested procedure for adjusting FM gain so as to preserve a 10 dB FM advantage. a) Using a 1000 Hz tone, measure output for 65 dBSPL input to the local microphone. b) Provide 65 dB SPL input to the remote microphone and adjust FM gain to give the same output (the two channels now have equal gain). c) Increase input to 80 dB SPL. If the output increases by 10 dB, the process is complete. If it does not, increase FM gain to give an FM advantage of between 5 and 7 dB (see text).