Class 1 vs Class Sound Level Meter: A Complete Guide

A sound level meter is an instrument designed to measure and quantify sound pressure levels. It converts acoustic signals (sound waves) into electrical signals and processes them to provide a readable measurement, typically displayed in decibels (dB).

There are mainly two types of sound level meters commonly used on the market: Class 1 and Class 2. These classifications are defined by international standards such as IEC 61672 and ANSI S1.4, based on different parameters such as their accuracy, frequency range, and tolerance limits.

Class 1 sound level meters meet the most stringent requirements. These instruments typically support a wide range of advanced features, including FFT analysis, octave and 1/3-octave band analysis, extended frequency response, audio recording, and a wider dynamic range. These capabilities make Class 1 meters essential for applications where precision is critical, such as professional acoustic analysis, regulatory compliance, and detailed environmental noise assessments.

Class 2 sound level meters, on the other hand, have a broader tolerance, making them suitable for more general-purpose use. They are commonly used for spot checks, basic surveys, or situations where exact precision is not required. While Class 2 meters may not offer the advanced features or accuracy of Class 1 devices, they are often more cost-effective and are perfectly adequate for everyday measurements and simpler field applications.

If your project requires defensible data for audits, legal purposes, or regulatory reporting, a Class 1 meter, such as Soft dB's SAS, is the recommended choice. If your needs are more focused on basic, cost-effective noise checks, a Class 2 meter like Soft dB's Piccolo offers a practical and reliable solution.

Class 1 vs Class 2 Sound Level Meter: Overview

There are two main types of sound level meters available on the market: Class 1 and Class 2. The table below provides a comparison of their typical differences based on several performance criteria.

Understanding the Key Technical Differences

Frequency Range & Frequency Weighting

In terms of frequency range, Class 1 sound level meters typically cover 16 Hz to 20 kHz, while Class 2 meters operate within a narrower range of 20 Hz to 8 kHz. This distinction is crucial for applications involving very low-frequency or high-frequency sounds, such as in industrial noise, environmental assessments, or tonal analysis, where Class 1 meters are better suited due to their extended range and precision.

Frequency weighting adjusts sound measurements to reflect human hearing sensitivity or to provide an unfiltered baseline:

• A-weighting simulates human hearing at low to moderate sound levels and is commonly used for general noise assessments;
• C-weighting reflects human hearing at higher sound levels and is often used for peak or impulse noise;
• Z-weighting provides a flat, unweighted response across the full frequency range and is used when no frequency adjustment is needed.

Both Class 1 and Class 2 meters can apply A, C, and Z-weightings, but Class 1 meters offer greater accuracy and a broader frequency response, making them the preferred choice for detailed and critical measurements.

Reference Frequencies & Tolerance Limits

Class 1 sound level meters comply with the strictest tolerance limits defined by IEC 61672, maintaining accuracy within ±1 dB in their optimal operating frequencies. In contrast, Class 2 meters are generally allowed a wider margin of around ±2 dB. While a 1 dB difference may appear minor, it can be critical in regulatory audits, legal disputes, or compliance testing, where precision directly impacts outcomes and potential penalties.

According to the IEC 61672 standard, the table below compares some reference frequencies and their corresponding tolerance limits for Class 1 and Class 2 sound level meters. We see that Class 1 maintains a precision of ±1 dB around 1000 Hz while this precision is rather ±2 dB for Class 2.

Measurement Range & Signal Processing

In terms of measurement range, both Class 1 and Class 2 sound level meters typically cover 30 to 130 dB SPL. However, Class 1 meters provide greater accuracy, particularly at low (<40 dB) and high (>120 dB) sound pressure levels, making them more suitable for environments with extreme noise conditions.

The two classes also differ in terms of electronic components. Class 1 meters typically feature precision condenser microphones, low-noise preamplifiers, and high-resolution 24-bit analog-to-digital converters. In contrast, Class 2 meters generally use basic microphones, higher-noise preamps, and lower-resolution analog-to-digital converters, which limits their accuracy and dynamic range.

Class 1 meters often include advanced display settings, real-time analysis, and extensive logging capabilities, while Class 2 meters tend to have a simpler user interface, basic functionality, and limited data storage.

Data Logging, Octave Band Analysis & Advanced Features

When it comes to data logging, octave band analysis, and other advanced features, Class 1 sound level meters typically offer enhanced capabilities, such as 1/3-octave band logging, FFT analysis, and other functions essential for detailed compliance testing and acoustic research.

However, in real-world field applications, factors like data logging capacity, battery life, calibration alerts, and compatibility with optional accessories often play a more critical role than the meter's class.

That's why all Soft dB instruments are designed to be rugged, durable, weather-resistant, and versatile, ensuring reliable performance under a wide range of deployment conditions.

Compliance, Standards & Legal Use

International & National Standards

A Class 1 sound level meter is a precision instrument that meets the highest accuracy requirements defined by IEC 61672 and ANSI S1.4. In comparison, a Class 2 meter allows for greater tolerances, resulting in lower measurement precision.

Compliance with these international standards is essential for applications involving audits, legal cases, and regulatory reporting. In addition to international guidelines, national regulations or regional standards may also apply, sometimes requiring even more stringent sound level limits or specific types of noise data collection.

Which Industries Require Which Class?

High-stakes projects, such as environmental impact assessments, construction noise compliance, and legal noise disputes, demand data that can withstand close scrutiny and exceed the precision limits of Class 2 meters. In these cases, Class 1 sound level meters are required. This also applies to sectors like aerospace, wind energy development, and urban planning, where high accuracy and regulatory compliance are critical.

For applications like occupational safety monitoring, general industrial noise spot checks, or basic environmental surveys, Class 2 meters are often acceptable. However, it is essential to verify local or national regulations before beginning any project, to ensure you're using the correct class of sound level meter for your specific application.

Class 1 or Class 2: Which One Is Best By Use Case

Workplace & Occupational Noise

For most industrial and commercial noise monitoring, Class 2 sound level meters are the preferred choice. They offer sufficient accuracy for environments like manufacturing floors, construction sites, and entertainment venues, while being more affordable and budget-friendly. Class 2 devices meet key standards such as OSHA, NIOSH, and ISO 9612, making them a practical solution for workplace noise assessments.

Environmental Noise Monitoring

Class 1 meters are essential for environmental noise assessments where precise data and legal compliance are critical. They meet IEC 61672 Class 1 standards, which are required for traffic noise studies, wind farms, airports, and urban planning projects. Many national regulations mandate Class 1 equipment for environmental assessments to ensure defensible and accurate results.

Precision Acoustics, R&D, Legal Evidence

When high-accuracy measurements are needed, Class 1 instruments are the standard. They're ideal for audio product testing, scientific research, lab analysis, and legal documentation. These meters offer tighter tolerances, wider frequency range and response, and support for octave-band analysis, making them indispensable for detailed acoustic studies.

Pricing & Value Considerations

Class 2 meters typically cost between $1,000 and $2,000, while Class 1 models range from $3,000 to over $8,000. Buyers should also consider recurring expenses like periodic certification, accessories and software licensing. Cutting corners can lead to inaccurate measurement data and potential compliance issues, which may cost far more in the long run.

Class 1 vs Class 2 Sound Level Meter: Remember Before Buying

Class 1 sound level meters are more precise. They are widely regarded as the gold standard for professional acoustic measurements, ideal when accuracy is critical, regulations are strict, or legal defensibility is required. In less demanding environments, a Class 2 meter often provides a practical and cost-effective solution.

The international standard IEC 61672 defines the performance and accuracy requirements for both classes. Class 1 meters offer superior precision, a wider frequency range, and better dynamic range, making them the go-to choice for high-stakes or regulatory work. Class 2 meters are suitable for general-purpose monitoring but may fall short in contexts requiring strict compliance.

Ultimately, the right sound level meter depends on your specific needs. Whether you're conducting routine environmental assessments or handling complex regulatory measurements, choosing the appropriate class ensures accurate, reliable data.

At Soft dB, we offer both options to match your application. Explore our latest Class 1 sound level meter, the SAS, or our Class 2 model, the Piccolo, designed for dependable performance at every level.

With decades of expertise in acoustics and vibration, we're here to help you make the right choice. Get in touch with our team for tailored guidance and ensure your measurements meet every expectation, with confidence.

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