Short press【A/B】button to switch A/B frequency,
Long press A frequency=B frequency.
Short press【NR】to turn on NR/NB, and then short press
to switch NR/NB.
Long press the【DSP】key to turn off NR/NB.
Short press【DSP】to set the NR/NB/PEAK threshold.
Short press the up and down direction keys to select the
NR/NB/PEAK setting item, and the left and right
direction keys to set the value.