Class 1 Sound Level Meter NL-53 / Class 2 Sound Level Meter NL-43
with Extended Function Program NX-43EX Instruction Manual Operation Guide

5.2 Sound level screen (sub channel display)

If you set one of the sub channels to [On] in the [Menu] screen - [Measure] - [Sub Channel Settings], the sound level L_p value of the sub channels will be displayed on the measurement screen (“Sub Channel Settings”).