Acoustic Calibrator for Sound Level Meters

What is the Acoustic Calibrator for Sound Level Meters?

A portable sound source that generates a stable tone, typically 94 dB at 1 kHz, to check and adjust the sensitivity of microphones and sound level meters. It is the right choice for field calibration checks before and after every noise measurement session.

Overview

The acoustic calibrator is a small battery-powered device that couples a precise sound pressure into the microphone cavity. Models conforming to IEC 60942 Class 1 provide 94 dB and 114 dB at 1 kHz with accuracy of ±0.2 dB, and some include multiple frequencies such as 250 Hz and 1 kHz. Adapters fit 1/2-inch, 1/4-inch and 1-inch microphones. Barometric pressure compensation corrects the level for altitude or weather, since the generated sound pressure changes with static pressure. Pistonphone types use a mechanical piston for higher stability, while electronic calibrators are lighter and cheaper. Calibrators themselves require annual verification against a reference standard, and calibration certificates support accreditation and regulatory use.

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?

• IEC 60942 Class 1 accuracy of ±0.2 dB gives reliable sensitivity verification.
• Dual levels of 94 and 114 dB check both low and high level linearity.
• Interchangeable adapters fit half-inch, quarter-inch and one-inch microphones.
• Built-in barometric compensation corrects level for altitude and weather changes.
• Automatic shutdown after calibration extends battery life in field use.
• Rugged carrying case protects the device and adapters during transport.

What are the technical specifications?

A typical acoustic calibrator for sound level meters configuration offers standard conformity of IEC 60942 Class 1, sound pressure levels of 94 dB and 114 dB, frequency of 1 kHz (250 Hz optional), level accuracy of ±0.2 dB, frequency accuracy of ±1% and total distortion of <1%. 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 Acoustic Calibrator for Sound Level Meters is used in field calibration checks, laboratory sound level meter verification, dosimeter calibration and monitoring station maintenance. 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/IEC 17025 calibration certificate available; 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 Acoustic Calibrator for Sound Level Meters?

Select a Class 1 calibrator when you use Class 1 meters or require legal traceability, and Class 2 for routine work with Class 2 meters. Multi-level models also check linearity. In an RFQ, specify class, levels, microphone adapters, pressure compensation 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.