Vernier SLM-BTA User 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.
2
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.
3
Operating the Sound Level Meter
Here are the general operating procedures:
1. Slide the power switch to the appropriate range.
2. Set the time weighting switch to “S.”
3. Set the maximum level hold switch to “RESET.”
4. Set the frequency weighting to “A.”
The Sound Level Meter functions as a standalone device, and you can monitor sound
levels
1
by reading the LCD panel. If you want to collect sound level data, you need
to connect the Sound Level Meter to a data-collection interface.
Connecting the Sound Level Meter to Vernier Products
The Sound Level Meter package includes a removable cable (order code
CB-SLM). Connect the mini-plug end of the cable into the bottom of the sensor.
Connect the other end to the data-collection interface, e.g., Vernier LabQuest
®
2,
Go!
®
Link, CBL 2™, or EasyLink®.
Collecting Data with the Sound Level Meter
This sensor can be used with the following interfaces to collect data.
Vernier LabQuest 2 or original LabQuest
®
a standalone device or with a
computer
Vernier LabQuest
®
Mini with a computer
Vernier LabPro
®
with a computer or TI graphing calculator
Vernier Go!
Link
Vernier EasyLink
Vernier SensorDAQ
®
CBL 2
TI-Nspire™ Lab Cradle
Here is the general procedure to follow when using the Sound Level Meter:
1. Connect the Sound Level Meter to the interface.
2. Start the data-collection software.
3. The software will identify the Sound Level Meter and load a default datacollection setup. You are now ready to collect data.
Data-Collection Software
This sensor can be used with an interface and the following data-collection software.
Logger Pro 3 This computer program is used with LabQuest 2, LabQuest,
LabQuest Mini, LabPro, or Go!Link.
Logger Lite This computer program is used with LabQuest 2, LabQuest,
LabQuest Mini, LabPro, or Go!Link.
1
A table of common sources of noise appears in the Additional References section of this
manual.
4
LabQuest App This program is used when LabQuest 2 or LabQuest is used as a
standalone device.
EasyData App This calculator application for the TI-83 Plus and TI-84 Plus can
be used with CBL 2™, LabPro, and Vernier EasyLink. We recommend version
2.0 or newer, which can be downloaded from the Vernier web site,
www.vernier.com/easy/easydata.html, and then transferred to the calculator. See
the Vernier web site, www.vernier.com/calc/software/index.html for more
information on the App and Program Transfer Guidebook.
DataMate program Use DataMate with LabPro or CBL 2™ and TI-73, TI-83,
TI-84, TI-86, TI-89, and Voyage 200 calculators. See the LabPro and CBL 2™
Guidebooks for instructions on transferring DataMate to the calculator.
DataQuest™ Software for TI-Nspire™ This calculator application for the
TI-Nspire can be used with the EasyLink or TI-Nspire Lab Cradle.
LabVIEW National Instruments LabVIEW™ software is a graphical
programming language sold by National Instruments. It is used with SensorDAQ
and can be used with a number of other Vernier interfaces. See
www.vernier.com/labview for more information.
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
Specifications
Sensor: ½" electret (prepolarized) condenser microphone
Power: four AAA batteries
Battery life: 50 hours typical
Display: 3½" LCD
Measurement range: Low: 35 dB to 90 dB
High: 75 dB to 130 dB
Frequency range: 31.5 Hz to 8000 Hz
Resolution: 0.1 dB
Accuracy: 1.5 dB (ref 94 dB @ 1 kHz)
Output: DC: 10 mV/dB
AC: 1.0 Vrms corresponding to the top of the
selected range
Stored calibrations
slope: 100 dB/V
intercept: 0 dB/V
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