With this technique:
-single microphone, either USB or XLR
-moving spatial average (wave microphone around by hand)
-at listening position (near driver's headrest)
-playing noise from REW or the wav file it produces
I like to use these settings on the generator:
-noise
-periodic pink noise
-full range
-sequence length 16k
-level -12dBFS RMS
Then (and only then) you can use these settings on the RTA window:
-mode 1/48th octave
-smoothing none
-fft length 16k (match the generator!)
-averages forever, while you wave the mic around
-window rectangular (only works for periodic noise if sequence and FFT lengths both match)
-max overlap 0%
To take a measurement:
-play noise in a loop either from REW's generator or the wav file it can create
-turn on the RTA by pressing the red record button
-wave microphone around the listening position slowly
-press the "reset averaging" button on the RTA window
-continue waving microphone around the listening postion
-wait until the RTA trace settles and stops changing a lot
(this is usually 10-20 averages or more)
-press the red record button to stop the RTA
-stop playing the noise
-on RTA screen, press save "current" trace
Finally, apply the smoothing you want:
-on the main REW screen, go to the "all traces" tab
-select all of the traces you've measured above
-open settings by pressing the gear icon
-change smoothing to 1/3rd-octave
-press apply smoothing
(experiment with other smoothing if you wish, I like 1/3rd or 1/6th sometimes)
View attachment 18089
View attachment 18088