Sound Level Meters Nor131 and Nor132 are designed and manufactured to the latest sound level meter standards and comprises two products.

The Nor131 is a Class 1 (precision) instrument whilst the Nor132 is designed in accordance with the less accurate Class 2 requirements. Both meters offer the same features with exception of the detachable preamplifier which is only available on the Nor131 version.



  • Noise hazards in the workplace
  • Prescription of hearing protection
  • Environmental noise investigations
  • Product noise testing
  • General purpose sound level meter
  • Reverberation measurement
  • Speech intelligibility


  • Single measurement range
  • Extremely simple operation
  • Parallel LAeq and LCpeak
  • Complies to IEC and ANSI standard
  • Real time 1/1 octave and 1/3 octave
  • Statistical analysis
  • Level versus time
  • Speech Transmission Index (STIPA) calculation
  • Reverberation time calculation
  • Large back-lit display
  • Large internal memory
  • USB interface
  • Multi language support


The Nor131 and Nor132 sound level meters may be extended with a selection of optional features that may be ordered and installed at any time.

Option 1: Frequency analysis – 1/1 octave filters

The Nor130 series of SLM’s may be extended with digital real-time 1/1-octave filters. This feature is available through the installation of option 1, and covers 12 frequency bands in the range from 8Hz to 16kHz.

Within each band, the instrument will measure the SPL, Leq, LMax, LMin and LE functions. Additionally, if the Option 2 Statistical analysis is installed, 8 different LN-percentiles are calculated within each 1/1-octave band.

  • A-preweighting feature available on display results.
  • All filters fulfill the IEC 61260 class 1 digital IIR base 10 requirements.
  • 120 dB “one-range” even in the filter bands.
  • Results are displayed both graphically and numerically.

Option 2: Statistical Analysis

  • Calculate 7 fixed LN values (L1%, L5%, L10%, L50%, L90%, L95% and L99%).
  • Parallel calculation of 1 editable LN value selectable within the range 0.1 – 99.9 %.
  • Statistical calculations based on 0.2 dB class widths covering the entire 130 dB range.
  • Parallel statistical calculation on both A- and C-/Z-weighted networks.
  • If real-time filters are installed (option 1 or 3), statistical calculations are available for the individual filter bands as well.

Option 4 adds statistical distribution to the Nor31/Nor132 functionality. There are eight percentiles shown, out of which one is user selectable. The class width is 0.2 dB over the entire 130 dB range.

The statistical distribution calculations employs the F time constant and applies to the spectral weighting networks (A and C or Z) as well as all the individual 1/1 and 1/3-octave filter bands (if applicable). The back-erase feature, which deletes up to the ten most recent seconds of acquired global data prior to a pause upon resuming, updates the statistics buffers as well to maintain consistency.

Nor131 and Nor132 Option 2 – The LN percentage table contains 7 fixed and one user-defined percentile

Option 3: Level vs Time

  • Simultaneous measurement of Global results and Profile results based on a level versus time values at preset intervals
  • Selection of preset intervals within the 1 second to 199 hours interval range
  • Automatic level versus time storage of LAeq, LAmax and LCpeak (or LZpeak)
  • Level versus time measurement continues during a paused Global measurement
  • Markers identify any pause, stop or continue of the measurement
  • To view or report the result simply transer the measurement result to PC using NorXfer and NorReview. Measurement results may also be automatically converted to Excel using NorXfer

Option 4: 1/3-octave real-time filters

The Nor130 series of SLMs may be extended with digital real-time 1/3-octave filters. This feature is available through the installation of option 4.

Within each band, the instrument will measure the SPL, Leq, LMax, LMin and LE functions. Additionally, if the Option 2 Statistical analysis is installed, 8 different LN-percentiles are calculated within each 1/3-octave band.

  • Parallel 1/3-octave real-time filters covering the 6.3 – 20000 Hz frequency range.
  • All filters fulfill the IEC 61260 class 1 digital IIR base 10 requirements.
  • A-preweighting feature available on display results.
  • 120 dB “one-range” even in the filter bands.
  • Results are displayed both graphically and numerically.

Option 5: Reverberation time measurement mode

Reverberation time measurement mode is now available on the sound level meter Nor131 and Nor132.

  • Reverberation time based on impulse excitation
  • Calculates both T20 and T30
  • Covers the 63 – 8000 Hz frequency bands for the 1/1-octave filters
  • Covers the 50 – 10000 Hz frequency bands for the 1/3-octave filter

Option 5 requires that option 1: 1/1-octave bands is installed!

Nor131 and Nor132 Option5 – Reverberation time measurement mode

Option 6: STIPA (Speech Transmission Index) measurement mode

  • Calculates the STIPA speech transmission index
  • Fulfils the requirements of the latest IEC 60268-16 (2011-6) Standard for STIPA
  • Includes signal (.vaw) for use through separate public address
  • Loudspeaker system or portable CD-player can be used for playback of signal
  • Background noise correction

It is now possible to use the Nor131 and Nor132 meters for analysing the Speech Transmission quality in public areas using the STIPA method. The method can be used to compare the speech transmission quality at various positions and under various conditions within the same listening space. The calculation follows the latest revision of the standard (2011-6).

A measurement in one listening position takes about 13 sec. Unlike many other STIPA measurement systems, the implementation with the Nor131/132 can also correct the results for the background noise. In addition all calculated indexes are displayed, not only the single STIPA value. This feature is valuable for engineers optimizing the room acoustics in public spaces or other areas where the speech quality is important.

Option 6 requires that option 1: 1/1-octave bands is installed!

Nor131 and Nor132 Option 6 – STIPA (Speech Transmission Index) measurement mode


The Nor130 series of SLM fulfil the following Sound Level Meter and 1/1&1/3 octave filter standards: IEC 60651, IEC 60804, IEC 61672, IEC 61260, ANSI S1.4, ANSI S1.11, ANSI S1.43, DIN45657. The Nor131 instrument meets the Class1 requirements while the Nor132 instrument the Class 2 requirements.

English, French and German language support.

Measured Parameters

Simultaneous measurement of SPL, Leq, LMax, LMin, LE and LPeak (plus the Tmax5 for Germany only).
Time weighting functions: Fast, Slow and Impulse.

Spectral weighting functions: Simultaneously measurement of A and C or Z-weighting. Additionally the 1/1 octave real time filters covering all bands from 8 Hz to 16K Hz (option 1) or 1/3-octave covering all bands from 6,3Hz to 20kHz (option 4).

Statistical calculations: 7 fixed percentiles L1%, L5%, L10%, L50%, L90%, L95%, and L99% plus one user defined value (f.ex. L0.1%). The statistical calculation is performed in real time within each frequency band if the filter option 1 is installed.

Measurement range

One range covering 120dB without any range adjustments.
Self noise measured with microphone: 17dBA (25dBA for Nor132)
Maximum RMS level: 137dBA
Maximum Peak level: 140dB PeakC
Levels up to 174dB can be measured by use of a suitable 1/4” microphone.

Battery / power consumption

Battery: 4 cells, IEC LR6, AA-sized, Alkaline batteries are recommended (e.g. Duracell Ultra M3). AA-sized NiCd or NiMH rechargeable batteries may be used, but must be charged outside the instrument. Battery voltage and time on battery since last change of bat-teries are indicated.
Typical battery life time (Duracell Ultra M3): 8 – 12 hours.

External dc: 11 – 16 volt. Power consumption approximately 1.2 watt dependent on selected modes of operation. External DC source should have source-impedance less than 1 ohm and be able to supply at least 300 mA. The mains adaptor Nor340 is recommended for use with the instrument.

If the external supply falls below 9 V, the instrument will use the internal batteries if available. If the instrument has switched off due to loss of power or insufficient supply voltage, the instrument will automatically switch on after reapplying the external DC supply.


The display is a monochrome, trans-reflective LCD graphical display with 160×240 pixels (W×H) with automatic temperature compensation for contrast and viewing angle. Pressing the light key illuminates the display. The light switches off automatically 2 minutes after the last operation of any key.
The bar graph display covers 80 dB, which may be scrolled in 10 dB steps to cover the total range.

Data storage / data transfer

Measured data is stored in the internal memory of the sound level meter. The memory is of the “flash” type retaining the information without battery supply. Approximately 5 Mbyte is available for the data storage. This corresponds 10 000 measurement for sound level meters without octave analysis and up to 2 500 for sound level meters with octave analysis.

Data transfer via USB 2.0 interface.

Analouge input

Input connector: TNC connector for Norsonic microphone systems.
Preamplifier: Nor1207 IEPE.
Polarisation voltage: 0 V (pre-polarized)
Supply current: 3mA
Supply voltage: 24V
Input impedance: > 100 kohm, <650 pF
Measurement range: 0.3 mV to 7 V (RMS) in one range corresponding to –10 dB to 137 dB with a microphone sensitivity of 50 mV/Pa. The maximum peak value ±10 V corresponds to 140 dB.
Microphone: Nor1228

Analouge output

The analogue output is a reproduction of the digitized input signal from the microphone (or input connector) obtained by a digital to analogue converter.
Output voltage: Full scale on the display corresponds to 100 mV.
Output impedance: The loading impedance shall be 16 ohm or greater. The output is short-circuit proof to GND.
Gain accuracy at 1 kHz: ±0.2 dB.
Frequency response re. 1 kHz: ±0.5 dB for 20 Hz < f < 16 kHz.

Environmental conditions

Reference conditions: The reference conditions for the instrument are as specified by IEC 61672-1 .
Temperature: 23°C
Humidity: 50% RH
Atmospheric pressure: 101.325 kPa

Environmental conditions for operation

Temperature: –10°C to +50°C
Humidity: 5% to 90% RH, dewpoint less than 40°C Atmospheric pressure: 85 kPa to 108 kPa

Environmental conditions for storage

Temperature: –30°C to +60°C
Humidity: 5% to 90% RH, dewpoint less than 40°C Atmospheric pressure: 50 kPa to 108 kPa


Depth: 29 mm
Width: 74 mm
Length, excl. microphone/preamplifier: 215 mm,
Length, incl. microphone/preamplifier: 305 mm
Weight incl. batteries: 380 g


Brochures / Product data

  • Broshure: Nor13x series


  • Brochure: Norsonic range of Sound Level Meters


Application notes

  • Application note: Noise at Work – Nor13x series


Type Approvals

  • PTB Germany type approval Nor131


  • METAS Switzerland type approval Nor131


  • Serbia type approval Nor131


  • BEV Austria type approval Nor132