Vernier SLM-BTA Manual

Sound Level Meter

(Order Code SLM-BTA)
The Sound Level Meter measures sound level in decibels. It
can be used for activities such as
 environmental noise studies
 sound level comparisons
 investigating room acoustics
 sound isolation modeling
 sound propagation modeling
Inventory of Items Included with the Sound Level Meter
Check to be sure that each of these items is included in your Sound Level Meter
package:
 Sound Level Meter
 Wind screen (black foam cover for the sensing element)
 4 AAA batteries (preinstalled in the meter)
 Cable to connect the sensor to a data-collection interface (order code
CB-SLM)
NOTE: Vernier products are designed for educational use. Our products are not
designed nor recommended for any industrial, medical, or commercial process such
as life support, patient diagnosis, control of a manufacturing process, or industrial
testing of any kind.
Sound Level Meter Description
The sensing microphone on the Sound Level Meter is located at the end of the silver
barrel at the top of the meter. Below the LCD, you will find three switches labeled
S/F, MAX/RESET, A/C. Below these switches you will find the power/measurement
range switch. Further description of these switches follows. The battery
compartment is located on the back of the Sound Level Meter. A signal output
terminal is located on the bottom of the meter. The output of this terminal is sent to
data collection interface.
The LCD panel displays noise levels in dB. A low battery level indicator and an
upper/lower range indicator are also displayed.
The sensor comes with a foam windscreen. The windscreen helps reduce the
detection of false high signals caused by wind blowing across the microphone. It
also protects the microphone from dust and debris.
Panel Switches
Power/Measurement Range Switch–This slide switch, labeled "O/35–90/75–130,"
turns the sensor on and sets the measurement range. When set to the 35–90 range
(LO), the sensor is designed to measure sound levels in the range of 35 to 90 dB.
When the switch is set to the 75–130 range (HI), the sensor is designed to measure
sound levels in the range of 75 to 130 dB. A range warning will appear if the
measured sound is beyond the range of the current setting. If this warning appears
continuously, set the switch to the appropriate range.
Time Weighting–The S/F switch just below the LCD sets the time weighting. For
normal measurements set the switch to the slow setting "S." For fluctuating noise,
set the weighting to fast "F." In the classroom, you will probably set it to "S."
Maximum Level Hold–Setting the MAX/RESET button to MAX sets the sensor
meter to show the maximum, weighted sound level. In the classroom you will
probably set it to RESET, in which case the display will continually display the
sampled reading. Setting this switch to MAX does not affect the output signal sent to
the data-collection interface.
Frequency Weighting–The A/C switch is used to set the weighting scale. "A"
weighted setting is the sound level value that most closely matches that of the human
hearing range. It is the weighting scale most commonly used for Occupational Safety
and Health Administration (OSHA) and Department of Environmental Quality
(DEQ) regulatory measurements. The "C" weighted scale is useful for monitoring
sources such as engines, explosions and machinery. This setting would also be used
if you wish to use the Sound Level Meter to get the total unweighted sound level of
the noise source.
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