Testo Sound Level MeasurementTesto Sound Level Measurement –

Measuring TipsMeasuring Tips

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New Sound Level Measuring Instruments testo 815 / 816New Sound Level Measuring Instruments testo 815 / 816

testo 815/816Applications 815Applications 816Basic ConceptBasic ConceptMeasuring Tips

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Application Areas testo 815Application Areas testo 815

testo 815

testo 815/816Applications 815Applications 816B i C t

Climate- and airconditioning i d t

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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

A li ti A 816Application Areas 816

testo 816

testo 815/816Applications 815Applications 816B i C t

workplace measurements

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industrial noise

environmental noise

classification measurements

neighbouring claims

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Basic Concepts: Sound Evaluation GraphsBasic Concepts: Sound Evaluation Graphs

Pegel (dB)testo 815/816Applications 815Applications 816B i C t

The frequency range in which a sound level meter measures according to IEC 60651 ranges

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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.

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 815/816Applications 815Applications 816Basic Concept Fast:

Long-term recording of the readings 1/8 s (125ms) and the value calculated therefrom is shown on the display

Basic ConceptMeasuring Tips

Zeit / TimeSi 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.

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 815/816Applications 815Applications 816B i C t specification of the pressure values would be unsuitable.

Therefore a logarithmic presentation is preferred.

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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

Basic Concepts: Acoustic Pressure / Sound LevelBasic Concepts: Acoustic Pressure / Sound Level

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jet

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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.

Basic Concepts: Accuracy Classes Standard DIN/IEC 60651Standard DIN/IEC 60651

testo 815/816Applications 815Applications 816B i C tBasic ConceptMeasuring 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)

Handling / Measuring Tipsg g p

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microphone alignment distance to body

According to DIN/IEC standard a sound level meter has to bepositioned 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 ybody of the measuring person.

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