BRUEL & KJAER 4212 Instructions And Applications page 13

The sound level is directly indicated in db SL, RMS on the instrument. The
output from the hearing aid is by means of the artificial ear fed to the
A.F. Spectrometer, which directly indicates the db SL of the hearing aid
output in RMS values. By recording the output voltage of the A.F. Spectro-
meter on the Level Recorder, the frequency characteristic is automatically
drawn on pre-printed frequency calibrated paper.
To adjust the measuring arrangement the following procedure should he
employed.
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