Class 1 Integrating Sound Level Meter

What is the Class 1 Integrating Sound Level Meter?

A handheld precision instrument meeting IEC 61672-1 Class 1 that measures Leq, Lmax and statistical levels with frequency and time weightings. It is the right choice for legal environmental noise assessment, acoustic consultancy and product noise testing where traceable accuracy is required.

Overview

This meter combines a pre-polarized free-field condenser microphone, preamplifier, digital signal processor and a color display in a handheld housing. It measures A, C and Z weighting with Fast, Slow and Impulse detectors in parallel, giving simultaneous readings of Leq, Lmax, Lmin, Lpeak and exceedance levels L5 to L95. Dynamic range of about 120 dB covers 20 to 140 dB in a single range without range switching. Data is stored on an SD card with time-history logging and optional audio recording to help identify events. Options add real-time octave and third-octave analysis and FFT. Conformity to IEC 61672-1 Class 1 and pattern approval documentation support legal use. Outputs include USB, Bluetooth and AC or DC signals.

How does it work?

A noise instrument converts sound pressure into an electrical signal with a calibrated condenser or MEMS microphone. The signal passes through frequency weighting filters, most commonly A-weighting that approximates human hearing, and C-weighting for peak and low-frequency content. A detector with exponential time weighting, Fast at 125 ms or Slow at 1 s, or an integrating stage produces the level in decibels relative to 20 µPa. Equivalent continuous level Leq, percentile levels such as L10 and L90, maximum and peak levels and sound exposure level are computed digitally. Class 1 instruments have tighter tolerances than Class 2 under IEC 61672-1. Octave or third-octave filter banks and FFT analysis add frequency information, and acoustic calibrators at 94 dB and 1 kHz check sensitivity. Permanent stations add weather protection and telemetry.

What are the key features?

• Single measurement range of 20 to 140 dB eliminates range-switching errors in the field.
• Parallel A, C and Z weightings with Fast, Slow and Impulse detectors record simultaneously.
• Time-history logging with audio recording aids event identification in environmental surveys.
• Optional real-time third-octave analysis supports building acoustics and tonal assessment.
• SD card storage and USB export provide traceable raw data for audit.
• Weatherproof windscreen and outdoor kit adapt the meter for long environmental campaigns.

What are the technical specifications?

A typical class 1 integrating sound level meter configuration offers accuracy class of IEC 61672-1 Class 1, measurement range of 20–140 dB(A), frequency range of 10 Hz–20 kHz, frequency weighting of A, C, Z, time weighting of Fast, Slow, Impulse and microphone of ½-inch pre-polarized condenser, 50 mV/Pa. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Class 1 Integrating Sound Level Meter is used in legal environmental noise assessment, acoustic consultancy, product and machinery noise tests and building and room acoustics. Across the wider Noise Monitoring class, laboratories also deploy it for community and environmental noise assessment, construction site noise compliance and occupational noise exposure surveys.

Which standards and certifications apply?

Relevant standards and methods include IEC 61672-1, IEC 61672-3, IEC 60942 (sound calibrators), ISO 1996-1, ISO 9612, IEC 61252 (personal exposure meters), GB 3096 and GB/T 3785.1. Certification candidates for this model are CE, China pattern approval and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Calibrate with an acoustic calibrator before and after each measurement session and record any drift, which should be under 0.5 dB. Use a windscreen outdoors, keep the microphone 1.2 to 1.5 m above ground and at least 3.5 m from reflecting surfaces for free-field environmental measurements, and avoid rain or condensation on the capsule. Record weather conditions because wind above 5 m/s invalidates many measurements. Instruments need periodic verification in an accredited laboratory, typically every one to two years, following IEC 61672-3. Store in dry conditions, replace batteries before long campaigns, and preserve raw time history when regulators may audit the data. Permanent stations require protection from birds, vandalism and lightning.

How do I select the right Class 1 Integrating Sound Level Meter?

Select Class 1 when measurements form legal evidence, are used in ISO 1996 assessments or require wide frequency coverage. Class 2 meters cost less and suit routine checks. In an RFQ, specify class, octave analysis, audio recording, calibrator, outdoor kit and accredited calibration certificate.

How does it compare with other Noise Monitoring variants?

Choose the class and type according to the regulation: Class 1 for environmental noise assessment and legal evidence, Class 2 for general surveys and workplace screening. Decide between handheld meters for spot checks, dosimeters for worker exposure and permanent stations for continuous site monitoring. Check the level range, such as 20 to 140 dB, and whether the dynamic range covers both background and peak events. For industrial and product noise, frequency analysis in octave or third-octave bands is needed. Consider data storage, time-history logging with audio recording for source identification, IP rating, temperature range and battery life. For permanent installations, evaluate microphone protection, communication and power. Confirm that the supplier offers IEC 61672-3 periodic verification and traceable calibration.