The document provides information about integrating sound level meters and measuring sound levels. It discusses decibels, frequency and time weighting, sound pressure levels, equivalent sound levels, and the key features and specifications of the SLM 100 sound level meter, including its data logging and plotting capabilities.

1. 11
Integrating Sound Level MeterIntegrating Sound Level Meter
Envirotech Instruments Pvt. Ltd
Measuring Sound Levels in
Free Field Conditions
SLM 100

2. 22
Decibel (dB)Decibel (dB)
Sound is measured as aSound is measured as a
ratio of pressure levels,ratio of pressure levels,
expressed in Decibelsexpressed in Decibels
dB = 20 log(pdB = 20 log(p2/p/p1) where,) where,
pp1 & p& p2 = sound pressure= sound pressure
Decibel scale describesDecibel scale describes
large ratios using numberslarge ratios using numbers
of modest sizeof modest size
Graph of 10log(P2/P1)
Envirotech Instruments Pvt. Ltd

3. 33
Frequency Weighting “dB (A)”Frequency Weighting “dB (A)”
Human ear perceives loudness of various frequencies differentlyHuman ear perceives loudness of various frequencies differently
Instrument must emulate human ear responseInstrument must emulate human ear response
Internationally used standardInternationally used standard for measuring/controlling noise levelsfor measuring/controlling noise levels
Envirotech Instruments Pvt. Ltd

4. 44
Time WeightingTime Weighting
Slow : 1 secSlow : 1 sec
Time (t)
SPL
(dB)
Time (t)
SPL(dB)
Fast : 125 msecFast : 125 msec

5. 55
SPL & LEQSPL & LEQ
SPL (Sound Pressure Level)SPL (Sound Pressure Level)
– Sound measured as pressureSound measured as pressure
– LLpp = 20 log (P= 20 log (Prmsrms/P/Poo), where,), where,
PPrmsrms= Root-Mean-Square Sound Pressure= Root-Mean-Square Sound Pressure
PPoo= Ref. Sound Pressure Level = 20= Ref. Sound Pressure Level = 20µµPaPa
LEQ (Equivalent Sound Level)LEQ (Equivalent Sound Level)
– Sound Levels integrated over timeSound Levels integrated over time
– Leq = 20 log [ (1/TLeq = 20 log [ (1/T∫∫PPrmsrms dt)/Pdt)/Poo ]]

6. 66
Principle Block DiagramPrinciple Block Diagram
Frequency weighted
input
Result in decibels
reference Po
Low-pass Filter
with one real pole
at -1/τSquare
Square
Root
Logarithm
Steps involved in Sound Level Measurement

7. 77
Sound Level Limits as per CPCBSound Level Limits as per CPCB
Category ofCategory of
Area / ZoneArea / Zone
Limits in dB (A) LEQLimits in dB (A) LEQ
Day Time Night TimeDay Time Night Time
Industrial AreaIndustrial Area 7575 7070
CommercialCommercial
AreaArea
6565 5555
Residential AreaResidential Area 5555 4545
Silence ZoneSilence Zone 5050 4040
Day Time shall mean from 6AM to 10PM, rest is Night time.

8. 99
How to Measure Sound?How to Measure Sound?
Free Field ConditionsFree Field Conditions
No reflections from wallsNo reflections from walls
No confined spaceNo confined space
Instrument should be away from bodyInstrument should be away from body
Adequate distance from sourceAdequate distance from source
While recording leave the instrumentWhile recording leave the instrument
on a stand for few hourson a stand for few hours

9. 1111
SLM 100 – Key FeaturesSLM 100 – Key Features
Integrating Sound Level MeterIntegrating Sound Level Meter
with Data Logging utilitywith Data Logging utility
Measures and Records SPL,Measures and Records SPL,
LEQ, SELLEQ, SEL
Runs on NiMH BatteryRuns on NiMH Battery
Can store upto 2000 samplesCan store upto 2000 samples
USB, RS232 Data TransferUSB, RS232 Data Transfer
.txt, .xls support.txt, .xls support
Histograms & ExceedanceHistograms & Exceedance
Curves plot utilityCurves plot utility
Simple & Friendly User InterfaceSimple & Friendly User Interface

10. 1212
SpecificationsSpecifications
Measurement Range :Measurement Range : 34 to 134 dBA in three 50DB34 to 134 dBA in three 50DB
overlapping ranges.overlapping ranges.
Error IndicationError Indication : Over Range, Under Range and Low: Over Range, Under Range and Low
Battery.Battery.
Accuracy / ClassAccuracy / Class : Type II designed for field use.: Type II designed for field use.
DisplayDisplay : LCD 2 Line-16 Character, with Backlight: LCD 2 Line-16 Character, with Backlight
Frequency WeightingFrequency Weighting : “A” type as per IS 15575: “A” type as per IS 15575
Time WeightingTime Weighting : SLOW 1 sec. and FAST 125 msec. as: SLOW 1 sec. and FAST 125 msec. as
per IS 15575 (Part1) 2005per IS 15575 (Part1) 2005
MeasurementsMeasurements : SPL, MIN SPL, MAX SPL, LEQ, SEL: SPL, MIN SPL, MAX SPL, LEQ, SEL
Data LoggingData Logging : LEQ, Min, Max, SEL recorded at 1min: LEQ, Min, Max, SEL recorded at 1min
intervals. Memory sufficient to record 24 Hr. data.intervals. Memory sufficient to record 24 Hr. data.

11. 1313
Firmware MenuFirmware Menu
RNG 1
RNG 2
RNG 3
Time Weighting
Slow
Fast
Operation Mode
Continuous Mode
Recording Mode
Battery Status
Batt Volts:
Est Time:
Factory Setup
CALIBRATION
Enter Batt Levels
Reserved
Menu
Select Range

12. 1414
Plot and Save HistogramsPlot and Save Histograms

13. 1515
Plot and Save Exceedance CurvesPlot and Save Exceedance Curves

14. 1616
Exceedance Curve & LnExceedance Curve & Ln
Often L10, L50…Ln valuesOften L10, L50…Ln values
are used as indices forare used as indices for
Noise PollutionNoise Pollution
Assessment.Assessment.
Software provided with theSoftware provided with the
SLM100 enables a simpleSLM100 enables a simple
readout of Ln values fromreadout of Ln values from
recorded data.recorded data.
In the example shownIn the example shown
L10 is 75 dbL10 is 75 db
L40 is 70 dbL40 is 70 db
L90 is 40 dbL90 is 40 db

15. 1717
Export to MS ExcelExport to MS Excel

16. 1919
Service SupportService Support
Envirotech InstrumentsEnvirotech Instruments
Envirotech East (P) LtdEnvirotech East (P) Ltd
Vaibhav Equipment ServicesVaibhav Equipment Services
Polu Enviro ServicesPolu Enviro Services
Eco Green SolutionsEco Green Solutions
B.K.Rao & AssociatesB.K.Rao & Associates

17. 2121
Thank YouThank You
Open for QuestionsOpen for Questions

18. 2222
PC System RequirementsPC System Requirements
Pentium 2 or abovePentium 2 or above
128 MB RAM128 MB RAM
4GB HDD (software takes ~ 1MB of HD space)4GB HDD (software takes ~ 1MB of HD space)
16x CD ROM Drive16x CD ROM Drive
2 button mouse2 button mouse
VGA Monitor (software runs best at a resolution ofVGA Monitor (software runs best at a resolution of
1024x768)1024x768)
RS-232 or USB ports for data transferRS-232 or USB ports for data transfer
Printer port (LPT) for printingPrinter port (LPT) for printing
OS – Windows 98, 2000, XPOS – Windows 98, 2000, XP
Java Run Time Environment (included in the installationJava Run Time Environment (included in the installation
CD)CD)

19. 2323
Transfer DataTransfer Data