This document provides an overview of sound level measurement using the testo 815 and 816 instruments. It discusses the basic concepts of sound level measurement including dB units, frequency weighting, time weighting, and accuracy classes. It also provides examples of application areas for the instruments and tips for proper handling and microphone positioning during measurements.

1. Testo Sound Level MeasurementTesto Sound Level Measurement –
Measuring TipsMeasuring Tips
www.testo.in

2. New Sound Level Measuring Instruments testo 815 / 816New Sound Level Measuring Instruments testo 815 / 816
testo 815/816
Applications 815
Applications 816
Basic ConceptBasic Concept
Measuring Tips
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3. Application Areas testo 815Application Areas testo 815
testo 815
testo 815/816
Applications 815
Applications 816
B i C t
Climate- and airconditioning
i d t
Basic Concept
Measuring Tips
industry
Use in trade enterprisesUse in trade enterprises
Measurements on office machineryMeasurements on office machinery
Measurement of machine noiseMeasurement of machine noise
Noise at combustion plants
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p

4. A li ti A 816Application Areas 816
testo 816
testo 815/816
Applications 815
Applications 816
B i C t
workplace measurements
Basic Concept
Measuring Tips
industrial noise
environmental noise
classification measurements
neighbouring claims
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5. Basic Concepts: Sound Evaluation GraphsBasic Concepts: Sound Evaluation Graphs
Pegel (dB)testo 815/816
Applications 815
Applications 816
B i C t
The frequency range in which a
sound level meter measures
according to IEC 60651 ranges
Basic Concept
Measuring Tips
Frequenz (Hz)
from31.5 Hz to 8000 Hz
The “ A” weighted graph corresponds to the hearing sensation
of the human earof the human ear.
In this connection the technician speaks of “correct hearing
volume”
The “C” weighted graph is used in case of many low
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The C weighted graph is used, in case of many low
frequencies within the acoustic signal.

6. Basic Concepts: Time Evaluation “Fast” or “Slow ”
1/8 s 1/8 s 1/8 s
Signal
1/8 s 1/8 s 1/8 s 1/8 s 1/8 s
Fast:
testo 815/816
Applications 815
Applications 816
Basic Concept Fast:
Long-term recording of the readings 1/8 s
(125ms) and the value calculated
therefrom is shown on the display
Basic Concept
Measuring Tips
Zeit / Time
Si l
therefrom is shown on the display.
1 sSignal
Slow:
Recording of the readings in 1 s (1000ms)
and the value calculated therefrom is
shown on the display.
The acoustic signal can be weighted timely “Slow ” (1000ms) or
“Fast” (125ms) in order to meet the requirements of the sound source
Zeit / Time
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Fast (125ms), in order to meet the requirements of the sound source.

7. Basic Concepts: The Measuring Unit dB
Sound are tiny pressure variations of the ambient air.
Basic Concepts: The Measuring Unit dB
As the human ear holds an extremely large dynamic range, the
specification of the pressure values would be unsuitable.
testo 815/816
Applications 815
Applications 816
B i C t
specification of the pressure values would be unsuitable.
Therefore a logarithmic presentation is preferred.
Basic Concept
Measuring Tips
The derived parameter is a handy figure, the decibel = dB
The decibel is not an absolute measuring unit (as e. g. °C) but
a ratio. A measured value is put into ratio of a reference value (sound
Example:
This equals how many dB?
reference value = 20 uPa).
meas. acoustic sound:
20.000 μPa
Log10 (1000) = 3
20.000 μPa
20 μPa
= 1000
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reference pressure level:
20 μPa
20 x 3 = 60dB

8. Basic Concepts: Acoustic Pressure / Sound LevelBasic Concepts: Acoustic Pressure / Sound Level
testo 815/816
Applications 815
Applications 816
B i C t
jet
Basic Concept
Measuring Tips
truck
air hammer
office
library
forest
The “measuring range” (dynamic complexity) of the human ear ranges
from 0 dB to approx 140 dB
hearing limit
from 0 dB to approx. 140 dB
In order to protect the health of mankind, ear protection has to be
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used at a (permanent) sound level of >80 dB.

9. Basic Concepts: Accuracy Classes
Standard DIN/IEC 60651Standard DIN/IEC 60651
testo 815/816
Applications 815
Applications 816
B i C tBasic Concept
Measuring Tips
The accuracy classes for sound level meter are internationally
standardised in the standard DIN/IEC 60651
The operating temperature range is -10...+50°C. Instruments working
in a range of 0...40 °C, receive a L as identification
Example: Class 2L
A sound level measuring instrument should be re-calibrated afterA sound level measuring instrument should be re-calibrated after
translocation or temperature changes. For that purpose special sound
calibrators are available
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testo 815 and testo 816 = Class 2 (+/-1.0 dB)

10. Handling / Measuring Tipsg g p
testo 815/816
Applications 815
Applications 816
B i C tBasic Concept
Measuring Tips
microphone alignment distance to body
According to DIN/IEC standard a sound level meter has to be
positioned in a zero degrees angle towards the sound source. That is,
the microphone points directly into the direction of the sound source.
In order to prevent interferences due to sound reflections on the body,
the measuring instrument should be held at least 30cm away from the
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g y
body of the measuring person.

11. Thank you
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