Digital noise correction Free

By subtracting the internal noise produced by the preamplifier and amplifier the noise threshold of a digital sound level meter may be considerably improved. Side‐by‐side measurements using a GenRad 1962‐9610 $12‐in.$ electret microphone and 1972‐9600 preamplifier with a Digital Acoustics DA 607 P V.03 Environmental Noise Monitor and a B&K 4145 1‐in. condenser microphone with a B&K 2209 Precision Sound Level Meter indicate a 19‐dB improvement in the noise floor of the Digital Acoustics device with digital correction. The noise threshold achieved was on the order of 13 dBA.