Noise Frequency Real Time Analyser Model 33

A powerful Class 1 instrument that measures 1:1 and 1:3 octave bands at the same time and is compliant with IEC 61672 and BS 4142 for industrial and environmental noise monitoring.

  • Incredibly precise measurements
  • Perfect for environmental assessments
  • 1:1 and 1:3 Octave Band Filters
  • Compliant to the latest Noise Regulations IEC 61672-1
  • High acoustic performance


A world of solutions – ideal for Industrial, Engineering, Vehicle, Environmental & Building Acoustics applications – Noise Frequency

The Model 33 Noise Frequency Real-Time Analyser with 1/1 & 1/3 Octave Band Filters simultaneously measures all parameters with all Frequency and Time Weightings, giving you the confidence you will always have the correct data for analysis. This high-performance meter offers exceptional acoustic performance but it is still easy to use; taking measurements is as simple as pressing the ‘record’ and ‘stop’ buttons.

The Real Time Analyser allows you to measure all Octave Bands at the same time, immediately capturing all of the data in each band and not missing any important information. This is very practical for reliable, accurate and rapid capture of variable noise levels to optimise environmental monitoring surveys or provide an accurate prescription of hearing protection in industrial environments.

For environmental noise monitoring under BS 4142:2014, the large memory, programmable auto repeat function and statistical LN values, combined with the optional addition of an outdoor kit, ensures the instrument is ideal for use as either a short-term or longer-term semi-permanent environmental monitor. The ability to take measurements every 125ms allows the user to conduct detailed analysis for engineering and environmental noise. It is also available with remote management so you can see the real-time noise Frequency measurements at your computer whilst taking measurements elsewhere.

The wide dynamic span of over 110dB in the single measurement range ensures you never make invalid measurements that ‘Overload’ or ‘Under range’ which is especially important during 1:1 or 1:3 Octave Band Analysis. An extensions module is available to enhance both the low and high frequency limits of the 1:3 Octave Band Filters so that frequencies as low as 6.5Hz up to 20kHz can be measured.

The two outstanding powerful software packages, Analyser and Acoustic Toolbox software allow you to download, analyse in depth and present your results in a variety of formats.

Features include:

  • Powerful measurement of Noise Frequency in real time
  • Compliant to the latest Noise Regulations IEC 61672-1 (Class 1), 61672-2 (Class 2) and BS 4141:2014
  • 1:1 and 1:3 Octave Band Filters
  • High acoustic performance
  • Large memory for data storage
  • Measurements every 125ms allowing detailed analysis
  • Available as Class 1 (Model 33) and Class 2 (Model 33-2)


Class1 Model 33

Class 2 Model 33-2

Applicable Standards

Type 1:

EN 60651:1994,EN 60804:2000,EN 61260:1995, IEC 61672-1:2002 Class 1

ANSI S1.4:1983, ANSI S1.43:1997, ANSI S1.11:1986

Type 2:

EN 60651:1994 EN 60804:2000, EN 61260:1995,IEC 61672- 1:2002 Class 2

ANSI S1.4:1983, ANSI S1.43:1997, ANSI S1.11:1986


Class 1 MK:224 Class+ Electret Prepolarised Condenser

Class 2 MK:216 Class+ Electret Prepolarised Condenser

Measurement Range

22dB(A) to 137dB(A), 23dB(C) to 137dB(C), 27dB(Z) to

137dB(Z), Peak to 140dB(C) or 168dB(C) as indication

Noise Floor (Typical)

17dB(A), 17dB(C), 22dB(Z)

Frequency Weightings

dB(A), dB(C) and dB(Z) to IEC 60651 Type 1

Time Weightings

F, S & I to Class 1 Tolerances




Backlit Graphical LCD


341mm x 82mm x 19mm


550g with batteries, 500g without batteries


2 x 1.5V size AA

Battery Life

Sound Level Meter Mode 15 Hours

1:1 Octave Band Mode 13 Hours

1:3 Octave Band Mode 11.5 Hours



  • Models 33 and 33-2 Broadband Mode – all functions are measured simultaneously
  • Sound Level LXY, Maximum Sound Level LXY max, minimum Sound Level LXY min
  • Equivalent Continuous Sound Pressure Level with Integration Time T LXT
  • Equivalent Continuous Sound Pressure Level of the entire measurement LXt
  • Sound Exposure Level LXE
  • Peak Sound Pressure Level LXpeak
  • Equivalent continuous sound pressure level with Impulse Time Weighting & Integration Time T LXIT
  • Equivalent continuous sound pressure level with Impulse Time Weighting of the entire measurement T LXIt
  • LXIT – LXT, LXIt – LXt, LXT –LAT, LCt – LAt
  • Measurement & Integration Time t & T
  • Percentiles L1, L5, L10, L50, L90, L95, L99 where X=dB(A), dB(C) & dB(Z) and Y=F,S & I
  • 1:1 Octave Band Mode – all functions are measured simultaneously
  • Equivalent continuous sound pressure level with integration time T LT in each 1:1 Octave Band
  • Percentile Levels & Overall Percentile Level in each 1:1 Octave Band Ln (where n = 1, 5,10, 50, 90, 95, 99)
  • Peak Sound Pressure Level Lpeak in each 1:1 Octave Band
  • Overall Equivalent continuous sound pressure level with integration time T LXT where X=dB(A), dB(C) & dB(Z)
  • Real Time Assessment of NC Curves
  • 1:3 Octave Band Mode All functions are measured Simultaneously
  • Equivalent continuous sound pressure level with integration time T LT in each 1:3 Octave Band



Operating Temperature -10°C to +50°C

Storage without Batteries Temperature -20°C to +60°C

Humidity 30 to 90% RH

External Connections

Model 33 & 33-2 RS232 Output and USB, External Power, AC Output


Pulsar ‘Acoustic Toolbox’ Download & Analysis software supplied as standard with all instruments


Ordering Codes

Sound Level Meter     Measurement Kit

Model 33                      Model 33K

Model 33-2                   Model 33-2K

Measurement kits include the Sound Level Meter, Model 105 or Model 106 Acoustic Calibrator, WS91 Windshield, K2 Attache Case, CP2 Carrying Pouch, Wrist Strap, Software, Download Cable, Batteries, Operating Manuals and Certificates of Calibration.

Optional Accessories

EFM33 Extended Frequency Module

RT33 Reverberation Time Module

WK1 Short Term Outdoor Kit

WK2 Long Term Outdoor Kit


With exceptional acoustic performance and compliance to the latest worldwide guidelines the Model 33 is perfect for the following applications:

  • Environmental noise monitoring
  • Tonal analysis of Environmental noise using 1:3 Octave Band Analysis
  • Industrial noise measurements
  • Accurate prescription of hearing protection using Real Time Octave Band Analysis
  • Building acoustic measurements (using the optional frequency analyser reverberation time module)
  • Vehicle noise testing using remote measurement abilities
  • Ideal for engineering applications such as noise control & reduction using 3D tonal analysis and the reverberation measurements.
  • Longer term outdoor noise measurements with optional weatherproof kits
  • Noise measurements down to Real-Time NC curve calculations.

Model 33.pdf



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