The sound is analysed on your device: nothing is sent.
Nothing kept here. Press “Keep” during a measurement, or import a file.
Display
What the spectrogram shows
Each column is the spectrum of a short piece of the sound (FFT, Hann window); a large FFT sees finer in frequency but blurrier in time. The colours go from black (quiet) to yellow (loud) through purple and orange: a palette that colour-blind people can read too, and in black and white.
Microphone calibration
Calibrate the microphone with the spectrum analyser (94 or 114 dB calibrator)
Audio input and measurement microphone
Device names appear after you first allow the microphone.
The file supplied with a measurement microphone (miniDSP UMIK-1, Dayton EMM-6, calibrated Behringer ECM8000…): lines of “frequency gain_dB [phase]”. The correction is applied before the weightings (sound level meter) and to every band (acoustics). Keep the same gain on the sound card as during calibration.