Sound Level Meter

A sound level meter is an instrument designed to provide a logarithmic measurement of sound pressure of a sound relative in decibels (dB) to a reference value.

It consists of four main components.  A microphone, preamplifier, signal processing and display.

Firstly, the Dewesoft Sound Level Meter (SLM) delivers sound and noise measurement to a class 1 standard.  Achieved by using the four main components (mentioned above).  Most importantly is the selection of microphone.  Dewesoft recommends a condenser microphone which reproduces a quality electrical signal at a low level.  This signal is made stronger by the preamplifier before it is processed by the main processor which is the Dewesoft X Software.  Signal processing includes applying frequency and time weightings to the signal.  This is specified by international standards such as IEC 61672-1, to which Dewesoft Sound Level Meters conform.

The main features of the Dewesoft Sound Level Meter include:

Meets Supported Standard; IEC 61672 Class 1 Sound Level Meter and IEC 60651, IEC 60804

Multiple Physical Measurement Parameters: The SLM provides measurements in air or water, vehicle bus systems, video, GPS and other maths to build a thorough image of your entire measurement.

High Dynamic Range: best in the business data acquisition hardware with 160 dB dynamic range in time and frequency domain.  Allows direct input of IEPE compatible microphones with support for TEDS automatic recognition.  The DAQ System is flexible and can be scaled for any number of microphones which can be calibrated with a calibrator.

Advanced Math – all at the same time: predefined standard frequency weighting A, B, C, D and Z; time weighting consisting of fast, slow or impulse, sound pressure levels, equivalent, peak, minimum & maximum sound pressure levels, sound energy, impulsivity of sound, statistical noise levels (LAF 1, 5, 10, 50, 90, 95 and 99% classes of values) – all available at the same time.

SLM Data Displayed in Real Time: flexible displays offering digital meters, analog bars, time domain recorders, narrowband FFT and octave analysers display data in real time as well as post processing.

Extra Services

IEC / ANSI Acoustic Calibration Services: Dewesoft offer traceable acoustic calibration services according to international IEC and ANSI standards.  Therefore, meaning your instrument accurately indicates the required measurement parameters.  Calibrations are documented, traceable and digital signed in cooperation with an accredited calibration lab.

Lifetime Free Software upgrades and support: Dewesoft’s Data Acquisition Systems come with world recognised, powerful Dewesoft X Data Acquisition Software.  Part of Dewesoft’s process is they offer lifetime FREE software upgrades and technical support to all users.

Local Sales and Support: Metromatics is Dewesoft’s Australian and New Zealand Partner and we offer local sales and support for the whole Dewesoft Product Range and can assist in setting this application up for you.


IEC 61672 Standard, Class 1

The SLM meets requirements of IEC 61672.  This standard specifies two levels of performance, Class 1 and Class 2.  Class 1 is more accurate.  The standard sets a range of performance criteria that the sound noise meter must meet along with the tolerances associated with it. Dewesoft’s sound meter and sound level software module allows calculations of typical parameters of the sound level measurements from a single microphone.  When combined with Dewesoft’s high end Data Acquisition System Hardware it meets all requirements to be categorised as a Class 1 Sound Level Meter.

Real Time Octave Filters

Additionally, the SLM provides real time octave filters.  This allows the analysis of signal and output frequency domain data. This option provides a time based real time octave band and 1/3 octave band measurements.  Other octaves can be post processed.

Calibration of Microphone Accurately using Dewesoft X Software

Over the lifetime of the device it is necessary to regularly calibrate the microphone accurately.  Achieved by using Dewesoft X Software.

  1. Calibration with TEDS
  2. With an External Microphone Calibrator
  3. With manufacturer calibration certificate – enter the sensitivity into the microphone channel configuration of the microphone.


Dewesoft provides professional certified IEC / ANSI acoustic calibrations for all your sound sensors.


Calculated Sound Parameters

The Dewesoft SLM calculates several parameters and channels in real time during the measurement.  Some of the automatic calculations are:

  • Frequency weighting
  • Time Weighting
  • LPK weighting – LLpkpk value = current maximum value of sound levels
  • Frequency Weighting Raw
  • Classified Sound Levels
  • Lp (SPL) – Time and frequency weighted sound pressure level scaled to dB value
  • Lim – Impulsivity of Sound = Impulse Weighted equivalent
  • LE – True value of which frequency weighted sound energy

More Information
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Finally, Metromatics proudly sell, service and support the Dewesoft product range in Australia and New Zealand.


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