Class 1 Sound Level Meter and Noise Measurement

The golden standard for sound noise level meter reimagined with the Dewesoft approach. Easy to set up and use while ensuring maximum accuracy with certified compliance with international standards. No matter the type of acoustics measurement, a sound level meter is always at the heart of the sound analysis.

Class 1 Sound Level Meter and Noise Measurement hardware and software from Dewesoft
Sound pressure
Sound pressure
USB 2.0
USB 2.0
High-speed video
High-speed video
Shock rating 100g
Shock rating 100g

Main Features

  • SUPPORTED STANDARD: IEC 61672 Class 1 sound level meter and IEC 60651, IEC 60804.
  • UNMATCHED FLEXIBILITY: SLM supports measurements in either air or water and can be combined with all other physical measurement parameters, vehicle bus systems, video, GPS and other math to build a thorough image of your entire measurement.
  • HIGH DYNAMIC RANGE: our top-of-the-class 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. Data acquisition system can be scaled for any number of microphones, microphones can be effortlessly calibrated with a calibrator.
  • ADVANCED MATH - ALL AT THE SAME TIME: predefined standard frequency weighting  A, B, C, D, and Z), time weighting (Fast, Slow or Impulse), sound pressure level, equivalent, peak, minimum & maximum sound pressure levels, sound energy, impulsivity of sound, statistical noise level (LAF1, 5, 10, 50, 90, 95 and 99 % classes of values) are all available at the same time.
  • RICH VISUALIZATION: flexible displays offering digital meters, analog bars, time-domain recorders, narrowband FFT and octave analyzers can be freely combined to show your SLM data in real-time as well as in post-processing.
  • IEC/ANSI ACOUSTIC CALIBRATION SERVICES: We offer traceable acoustic calibration services according to international IEC and ANSI standards and ensure that your instrument accurately indicates the required measurement parameters. Calibrations are documented, traceable and digitally signed in cooperation with accredited calibration laboratory.
  • LIFETIME FREE SOFTWARE UPGRADES AND SUPPORT: Our data acquisition systems come bundled with award-winning Dewesoft X data acquisition software. The software package is always evolving and new features are being added. We offer lifetime FREE software upgrades and technical support to all our users.

Class 1 Sound Level Meter

Class 1 sound level meter is designed to meet the requirements of IEC 61672. This standard specifies two levels of performance, Class 1 and Class 2, with Class 1 being effectively more accurate.

Within the standard are a set of performance criteria that a sound noise meter must meet and each of these has a tolerance associated with it.

Dewesoft sound meter and sound level software module allows calculating typical parameters for the sound level measurements from a single microphone. It offers typical sound level meter calculations.

Together with our high-end DAQ system hardware, it fulfills all the requirements for Class I sound level meter.

    Real-time Sound Analysis

    Dewesoft sound level meter solution provides real-time octave filters in order to analyze a signal and output frequency domain data. The  Octave Analysis option provides a time-based realtime octave band and 1/3 octave band measurements.

    Additionally, 1/n octave can be post-processed for requirements that need 1/6 octave, 1/12 octave, and 1/24 octave band spectral analysis.

    Microphone Calibration

    In order to make scientific sound measurements with a microphone sensor, a precise microphone sensitivity must be known. Microphone calibration will enable confidence in the performed measurements.

    Since the calibration may change over the lifetime of the device, it is necessary to regularly calibrate the measurement microphone accurately.

    Our solution allows a microphone to be calibrated in several different ways inside the Dewesoft X software:

    • Calibration with TEDS: the sensitivity of the microphone is written on the TEDS chip, the software will read it.
    • With an external microphone calibrator: calibration of the microphone is possible directly with the microphone calibrator directly inside our Dewesoft X data acquisition software.
    • With manufacturer calibration certificate: simply enter the sensitivity into the microphone channel configuration of the microphone.

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

    Frequency Weighting Analysis

    Frequency weighted noise measurements offer convenient ways to measure sound and sound frequency range. Dewesoft uses each of these frequency weighting algorithms for different types of measurements.

    • A-weighting is applied to measured sound levels in an effort to account for the relative loudness perceived by the human ear. The human ear is less sensitive to low and high audio frequencies.
    • B-weighting is the best weighting to use for music listening purposes.
    • C-weighting is used for high-level noise measurements.
    • D-weighting was specifically designed for use when measuring high-level aircraft noise in accordance with the IEC 537 measurement standard. The large peak in the D-weighting curve reflects the fact that humans hear random noise differently from pure tones, an effect that is particularly pronounced around 6 kHz.
    • Z-weighting is linear at all frequencies and it has the same effect on all measured values.

    Time Weighting Analysis

    Sound level measurement using any grade of a sound level meter can be fast, slow, or impulse time-weighted. These weightings date back to the time when sound level meters had analog meters and defined the speed at which the meter moved.

    • Fast: the needle would move fast to show quickly varying noise. Fast corresponds to a 125 ms time constant.
    • Slow: the needle would be damped to smooth the noise out to be easier to read. Slow corresponds to a 1-second time constant.
    • Impulse: the impulse time weighting is about four times faster than Fast, with a short rising time constant but a slow falling constant. Impulse has a rise time constant of 35 ms and fall time constant of 1,5 s.


    Calculated Sound Parameters

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

    • Frequency weighting: LFTp - time and frequency weighted sound pressure level (SPL) already scaled to decibel (dB) value.
    • Time weighing
    • Lpk weighting: LLpkpk value, which shows the current maximum value of the sound levels.
    • Frequency weighting raw: F weighted raw value shows the frequency weighted time curve of sound in the Pascal units. 
    • Classified sound levels: Classified sound levels. Each calculated value is put in the classes and then we can choose to see LAF 1, 5, 10, 50, 90, 95 and 99% classes of values.
    • Lp (SPL): Time and frequency-weighted sound pressure level (SPL) already scaled to the dB (decibel) value.
    • Lim: This value tells the impulsivity of the sound and is the impulse-weighted equivalent.
    • LE: This is the value which is the frequency-weighted sound energy.

    True Peak Level

    The true peak level shows the real peak value of the input signal in dB (decibel). The sound pressure level (SPL) always contains a time weighting filter, which has an influence on the peak value.

    The sound pressure level does not reach that high values, no matter if we select F, S or I time weighting. The LCpk, however, shows the “true peak”. 


    What is a sound level meter?

    A sound level meter is used for acoustic sound measurements. Sound level is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. It is measured in decibels (dB) above a standard reference level.

    A sound level meter (SLM) is an instrument (commonly hand-held) that is designed to measure sound levels in a standardized way. It responds to sound in approximately the same way as the human ear and gives objective, reproducible measurements of sound pressure levels.

    Sound level meters require a microphone sensor to measure the sound. The best type of microphone for sound level measurement is the condenser microphone, which combines precision with stability and reliability.

    How does a sound level meter work?

    A sound level meter uses four main components - a microphone, a preamplifier, signal processing, and a display. The microphone converts the sound signal to an equivalent electrical signal. The most suitable type of microphone for sound level meters is the condenser microphone, which combines precision with stability and reliability. The electrical signal produced by the microphone is at a very low level and made stronger by the preamplifier before it is processed by the main processor typically software. 

    Signal processing includes applying frequency and time weightings to the signal as specified by international standards such as IEC 61672 – 1, to which sound level meters conform.

    What is sound pressure and sound pressure level?

    Sound pressure or acoustic pressure is the local pressure deviation from the ambient (average, or equilibrium) atmospheric pressure, caused by a soundwave. In the air, sound pressure can be measured using a microphone, and in the water with a hydrophone. The unit for the sound pressure is the pascals (symbol: Pa).

    Sound pressure level (SPL) or sound level is a logarithmic measure of the effective sound pressure of a sound relative to a reference value. It is measured in decibels (dB) above a standard reference level. The standard reference for the sound pressure in an air or other gases is 20 µPa, which is usually considered the threshold of human hearing (at 1 kHz). Learn more.

    Which standards does the Dewesoft sound level meter supports?

    Dewesoft sound level meter supports the following international standards - IEC 61672 and IEC 60651, IEC 60804. This makes it the Class 1 sound level meter.

    Does Dewesoft sound level meter include software?

    Yes. Dewesoft sound level meter includes advanced and easy to use sound recording, sound analysis, and visualization software. It offers real-time sound processing and analysis. The software is included for free and offers free upgrades forever. Evaluation version with full functionality can be downloaded for a trial run.

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