How To Select The Right Sound Level Meter Class For Laboratory Use

How to Select the Right Sound Level Meter Class for Laboratory Use

In a laboratory environment, selecting a sound level meter is not simply about picking the “cheapest” or “most popular” model. You must align the meter’s accuracy class, measurement capabilities, data-logging functions and calibration traceability with your specific application, regulatory requirements and long-term usage scenario. Below we provide a practical selection framework and recommendations tailored to common laboratory scenarios.

Core Concepts You Should Know

Accuracy Classes – Class 1 vs Class 2

International standard IEC 61672-1 (Electroacoustics – Sound Level Meters – Part 1: Specifications) defines two performance categories (Class 1 and Class 2) for sound level meters.

“Class 1” meters have tighter tolerances, broader frequency range, and better stability than “Class 2”.
“Class 2” meters are still compliant, but for more general use and not necessarily precision laboratory measurement.
Older standards (e.g., IEC 60651) used “Type 1/Type 2” terminology; under IEC 61672 these become “Class 1/Class 2”.

Hence, when you see a meter labelled “Class 1 (IEC 61672-1)” or “Class 2”, that gives you a key indication of its measurement fidelity.

Frequency Weighting & Time Weighting

Frequency weighting: SLMs typically offer A-, C- and Z-weighting. A-weighting (dB(A)) is commonly used for human-noise response and environmental/occupational noise assessments.
Time weighting: “Fast”, “Slow” (and sometimes “Impulse”) modes define how the meter smooths fluctuations in the sound pressure level.
For laboratory settings, you may also require built-in functions for equivalent continuous sound level (Leq), peak levels, octave-band or 1/3-octave-band filters if you are analysing frequency content.

Data-Logging, Analysis & Traceability

In a laboratory, besides simply reading an instantaneous decibel value, you often need:

Time-stamped records for reporting
Statistical functions (L10, L50, L90, percentile levels)
Data export (USB, Ethernet, WiFi) for post-analysis
Calibration traceability (i.e., calibrator certificate, model’s pattern approval)
These features elevate the device from a “survey instrument” to a laboratory-grade measurement tool.

Common Laboratory & Monitoring Scenarios and Class Recommendations

Precision acoustics research or materials testing

If your lab is doing high-end acoustics research, validating material sound absorption/insulation or supporting regulatory compliance → choose a Class 1 sound level meter.
Why: The broader frequency response, lower maximum uncertainty and higher stability are key when measurement errors must be minimised.
Features to look for: wide dynamic range (e.g., 10 Hz–20 kHz or beyond), octave/1/3-octave filters, integrated logging, calibrator traceable to national standards.
Long-term tip: Build a calibration schedule, keep environmental conditions stable (temperature/humidity), and perform repeated verification.

Teaching lab, basic environment noise monitoring

For classroom demos, introductory acoustic labs or routine monitoring where ultra-precision is less critical → a Class 2 sound level meter may suffice.
Why: Cost-effective and simpler to operate, still compliant with IEC 61672 for many applications.
But: If you later intend to publish or certify results, you may need Class 1 anyway.

Engineering/industrial site visits from lab

If your lab instrument will also be used for field visits (site noise, operator exposure) → you might choose a Class 1 meter (so that you cover the highest requirement) or a robust Class 2 with known limitations.
Tip: Check whether your national or local regulation mandates Class 1 for certain noise levels (e.g., when measuring below 35 dB(A) in some jurisdictions).
In fact, in China environment noise standards indicate that when A-weighted sound levels drop below ~35 dB, a 1-level instrument may be required.

Long-term environmental monitoring / data-logging

When the objective is tracking trends over weeks/months rather than point measurements, you still need good stability, data-logging and remote interface.
Choice: Class 2 may work if the measurement accuracy tolerance is acceptable, but given the long term drift and data value you may prefer a Class 1 for confidence.
Key features: remote access, automated scheduling, built-in self-test, anti-drift calibration reminder, long battery or mains option.

Selection Checklist for Sound Level Meters

Standards & Compliance

Ensure the instrument specifies compliance to IEC 61672 (or your national equivalent like EN 61672, ANSI/ASA S1.4) for either Class 1 or Class 2.
If you will publish or submit results to regulatory bodies, check they accept the meter’s class for your measurement scenario.
Ensure the meter’s manufacturer provides a pattern approval certificate or equivalent.

Accuracy & Uncertainty

Confirm the meter’s performance band: frequency response, dynamic range (dB span), temperature/humidity operating conditions.
Ask for manufacturer’s specification for measurement uncertainty (±x dB) and repeated-measurement reproducibility.
Plan for calibration: does the supplier provide calibration options traceable to National Metrology Institute?

Frequency & Time Weighting, Band Analysis

Ensure the meter supports A-weighting (dB(A)), and if required, C-weighting and Z-weighting.
If required for your lab, ensure you have octave/1/3-octave band filters (for low-frequency noise, HVAC, emission labs).
Check time weighting options (Fast, Slow, Peak, Impulse) and ability to compute Leq, L10, L90, SEL etc.

Data & Interface

Data logging: memory capacity, sampling interval, timestamp, format (CSV, binary), interface (USB, RS-232, Ethernet, WiFi).
Software support: compatible for data import/export, statistical analysis, report generation.
Remote operation: if you’ll mount the meter in a remote lab space, check for remote control or data streaming capability.

Calibration & Maintenance

Choose a meter with accessible calibration routine; calibrator should itself be traceable.
Plan for periodic calibration or verification (intervals recommended e.g., annual or bi-annual).
Ensure documentation of calibration certificates, versioning, model number and serial number for audit trail.

Practical and Durability Considerations

Ensure measurement range suits your lab environment (e.g., if very quiet < 30 dB or noisy > 130 dB).
Consider microphone type, mounting (tripod vs handheld), self-noise of the instrument (important for low-level labs).
Consider durability: Is the meter portable or bench-mounted? Are there environmental protections (dust, humidity, shock)?
Consider cost vs lifetime: Higher class (Class 1) instruments cost more but deliver better stability and value for critical measurement tasks.

Deployment Advice for Laboratory Setup

Define your primary use case: Are you doing high-precision research, regulatory compliance, teaching, or long-term monitoring? That will guide class choice.
Budget wisely: Allocate budget not just for the meter, but for accessories (calibrator, tripod, software), calibration, and maintenance.
Field-test before purchase: If possible, request a demo or sample measurement in your lab environment to verify noise floor, microphone placement, and user interface.
Establish a calibration / verification schedule: Document staff training, calibration records, measurement procedures and ambient conditions.
Implement measurement protocols: For example, microphone placement (height, distance from reflecting surfaces), measurement duration, statistical handling of data.
Plan for future expansion: If you might expand into 1/3-octave analysis or higher-end noise research, consider choosing a meter with that capability (or upgrade path) from the start.

Frequently Asked Questions

Q1: Can we use a Class 2 meter in the lab for all tasks?
Yes for many routine monitoring or teaching tasks. But if your measurements must feed into published research, regulatory compliance, or very low/high-level sound measurement, a Class 1 meter is strongly recommended (or required by regulation).

Q2: What is the difference in tolerances between Class 1 and Class 2?
The tolerance (maximum deviation) allowed for Class 2 is larger than for Class 1. In general Class 1: tighter error margin, broader frequency response, wider dynamic range.

Q3: How often should a sound level meter be calibrated?
Typically annually or biennially, depending on usage, manufacturer’s recommendation and criticality of measurement. Using a calibrator before each major measurement session is also good practice.

Q4: Why is A-weighting used so often (dB(A))?
Because A-weighting corresponds more closely to human ear sensitivity and is widely mandated in environmental and occupational noise standards.

Q5: My lab measures very low sound levels (below 35 dB(A)). Does that affect class requirement?
Yes. Some regulations specify that when sound levels are very low (e.g., < 35 dB(A)), you should use a higher-accuracy (Class 1) meter because the margin of measurement error becomes more significant relative to the signal level.

Q6: Does the Class 1 meter always produce “better” measurements regardless of environment?
A Class 1 meter offers better specification, but only if used correctly (correct placement, calibration, environment). For some lab tasks, a Class 2 meter sufficiently meets the required accuracy. It’s about matching the tool to the requirement, not always “the best is always best”.

At Honeytek, we specialise in precision electronic measurement tools.