407732 Datasheet, PDF (5/6 Pages) Extech Instruments Corporation. – Digital Sound Level Meter

Operation
1. Power the meter by pressing the power button. The meter will begin displaying
sound level readings. If the LCD does not switch on, check the 9V battery located in the
rear battery compartment.
2. Hold the meter in hand facing the microphone toward the source of the sound to be
measured.
3. View the measurement on the meter’s LCD. An indication of OVER means that the
measurement is out of range. Toggle the ‘Hi’ (65 to 130dB) and ‘Lo’ (35 to 100dB)
measurement ranges using the HI/LO button. For measurements in the 65 to 100dB
region either range can be used.
‘A’ and ‘C’ Frequency Weighting
Use the ‘A/C’ button to select ‘A’ or ‘C’ frequency weighting. With ‘A’ weighting selected,
the frequency response of the meter is similar to the response of the human ear. ‘A’
weighting is commonly used for environmental or hearing conservation programs such as
OSHA regulatory testing and noise ordinance law enforcement. ‘C’ weighting is a much
flatter response and is suitable for the sound level analysis of machines, engines, etc.
Most noise measurements are performed using 'A' Weighting and SLOW Response.
‘FAST’ and ‘SLOW’ Response Time
Use the ‘F/C’ button to select FAST (125 ms) or SLOW (1 second) response time. Select
FAST to capture noise peaks and noises that occur very quickly. Select the SLOW
response to monitor a sound source that has a consistent noise level or to average quickly
changing levels.
Select Slow response for most applications.
‘Hi’ and ‘Lo’ Range Selections
Use the ‘Hi/Lo’ button to select the appropriate range. If the measurement is in the range
of 35 to 100 dB, use the ‘Lo’ range. If the measurement is between 65 and 130dB, use the
‘Hi’ range. For measurements between 65 and 100dB, either range can be used. If the
display flashes the OVER icon, press the range button to toggle the range.
MAX HOLD
In this mode, the meter only updates the LCD when a higher reading than the one
presently on the display is detected. Select MAX HOLD by momentarily pressing the MAX
HOLD button. The meter displays the MAX icon when in the MAX HOLD mode. Press the
MAX HOLD button again to exit this mode (the MAX indicator will switch off).
DATA HOLD
To freeze a displayed reading, press and hold the MAX HOLD button until the MAX and
HOLD display icons appear. To release the display and return to the normal operating
mode, press and hold the MAX HOLD button until the MAX and HOLD icons switch off.
Backlight button
The LCD is equipped with backlighting for easier viewing, especially in dimly lit areas.
Press the backlight button to turn the backlight on. Press again to turn the backlight off.
The backlight does not have an automatic power down function; judicious use will
conserve battery life.
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Model 407732 Version 1.4 June 2004