General DSM8930 User Manual page 5

Fig. 2. All possible display indications and their meanings
MAX Digital readout is highest level recorded since
meter was powered on
MIN Digital readout is lowest level recorded since
meter was powered on
SPL Abbreviation of sound pressure level (the
parameter measured)
Meter's battery is very low on charge and should
be replaced
dB Sound level unit (accompanies reading at its left)
40 Range Baseline (low end of current measurement
range, in dB). "40" indicates 40 to 70 dB range;
other possible numbers at this position are 60 (for
60 to 90 dB range), 80 (for 80 to 110 dB range)
and 100 (for 100 to 130 dB range)
+0, +10, Labels of analog bar graph scale. Indicate
+20, +30 amplitude of input (in dB) relative to low end of
measurement range above left end of graph
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