How to choose
the best sound level meter?

A sound level meter, also known as a sound meter, noise meter, decibel meter, or sound pressure level (SPL) meter, is a measuring instrument that is designed to measure sound levels in a standardized way. It is widely used in industries such as construction, transportation, and entertainment to measure noise levels and ensure compliance with regulations and standards.ff

What is a sound level meter?

A sound level meter (SLM), also known as a sound meter, noise meter, decibel meter, or sound pressure level (SPL) meter, is a measuring instrument that is designed to measure sound levels in a standardized way. Following IEC 61672, sound level meter is composed of a microphone, a preamplifier, a signal processor, and a display that displays noise results. Hand-held noise level meters are usually battery-powered and feature a triangular tip and windscreen on top. 

A sound level meter is a device that measures time-averaged or exponential time-weighted sound levels, frequency-weighted noise levels, and frequency-weighted average noise exposure levels.

What does a sound level meter do

What does a sound level meter measure?

A sound level meter is a device that measures:

  • time-averaged or exponential time-weighted sound levels
  • frequency-weighted noise levels
  • frequency-weighted average noise exposure levels.

How sound level meter measures sound?

A sound level meter microphone detects the air pressure changes and converts them into electrical signals, which are then converted into digital signals using an A/D converter. The signal processor processes the digital signals, and the standard sound level meter uses a root-mean-square (RMS) circuit to convert the AC signal from the microphone to a DC signal. The most common result obtained from a sound level meter is the Sound Pressure Level (SPL) which is expressed in decibels (dB). The SPL provides a measure of the magnitude of sound pressure variations in a given environment. Integrating or integrating-averaging sound level meters can be used to measure equivalent continuous sound level (LEQ), which represents the average sound level over a specified period of time.

Is SLM a noise measurement device?

A noise measurement device is a broader term that can refer to any device that measures sound, including sound level meters, noise dosimeters or environmental noise monitors. However, sound level meters are specifically designed to measure sound levels in a standardized way and give objective, reproducible measurements of sound pressure levels. So, while all sound level meters are noise measurement devices, not all noise measurement devices are sound level meters.

Noise measurement applications

The following are the most common types of professional sound measuring applications for sound level meters:

Table of Contents

The price of a professional sound level meter can vary depending on several factors, such as its level of accuracy and features. A high-end Class 1 SLM, which offers the most accurate readings and a wide range of features, can cost anywhere from $3000 to $9000. The most expensive Class 1 meters can cost upwards of $6000 to $9000. Mid-range Class 1 meters, which offer good accuracy and a limited set of features, can cost between $3000 to $6000. If you’re looking for a more affordable option, a Class 2 sound level meter, which is less accurate but still suitable for many applications, can be purchased for a price range of $1500 to $2000. Ultimately, the price you’ll pay will depend on your specific needs and the level of accuracy and features required for your application.

A sound level meter is a device that measures various types of noise levels, including time-averaged or exponential time-weighted sound levels, frequency-weighted noise levels, and frequency-weighted average noise exposure levels. It is also known as a noise meter, sonometer, or dB meter, and consists of a microphone, a preamplifier, a signal processor, and a display that displays noise results.

What is the best sound level meter for me?

It can be a challenge to find the right sound meter for your specific needs. First, you must decide how the noise meter will be used. Typically, professional sound pressure measurements follow standardized procedures that provide requirements for the type of sound meter. If you need to measure noise for your interests, a mobile application is just as good as purchasing a market decibel level meter.

How do I choose the right sound level meter for my needs?

There are a few factors to consider when choosing a noise level meter:

What type of noise environment will you be measuring?

If you’re measuring environmental noise, you’ll need a Class 1 meter.
For industrial sound measurements, you’ll probably use a Class 2 sound meter.

What range of sound pressure levels do you need to measure?

Most sound level meters have a noise levels range of 30-130 dB.
The range that you need depends on the object you are measuring.
For environmental noise measurements, you may need a lower range than 25 dB but not necessarily up to 140 dB.
In the case of industrial noise, you will need the upper level to be at least 140 dB.

What is your budget for a sound level meter?

Class 1 meters are more expensive than Class 2,
but both will give you accurate sound measurements as long as they meet the requirements of the IEC 61672-1 standard.

What is the smallest and largest operation range I'll need?

For environmental noise measurements, you may need a lower range than 30 dB but not necessarily higher than 130 dB. In the case of industrial sound, you will need the upper level to be at least 140 dB Peak (the highest sound pressure level).

Do I need a class 1 or class 2 sound level meter?

Depending on the measurement application, you will use class 1 or class 2. Class 1 is required for environmental noise and building and room acoustics. For occupational noise, class 2 is usually accepted unless the noise is dominated by high frequencies. If sound level measurements are taken in negative temperatures, class 1 is required.

What is a frequency analysis for?

Professional sound level meters (SLMs) can do frequency analysis as well as measure sound pressure levels. This allows the frequency range to be divided into sections or bands, providing more detailed information about complex sounds. The display of an SLM typically shows a spectrum of the sound being measured, usually divided into 1/1 or 1/3 octave bands, with a decibel (dB) level indicated for each frequency band. This provides a more detailed and accurate understanding of the sound being measured, as different frequencies can have different effects on human perception and can contribute differently to overall noise levels.

Frequency analysis is often used in various types of professional sound measurements, such as building acoustics or environmental measurements. However, it may not be necessary in all situations (for example in occupational noise measurements), and the specific measurement requirements will depend on the application and standards being followed.

What are the different types of sound level meters?

  • Class 1 Sound Level Meters: the most precise and most expensive noise level meter, meeting IEC 61672-1 standard and having a type approval
  • Class 2 Sound Level Meter: a less accurate and less expensive noise level meter that meets IEC 61672-1 standard
  • Low-cost sound meters which do not conform to IEC 61672, usually sold in markets

Types of pro sound meters

There are two main types of pro sound meters:

  • Class 1

These are the most accurate and expensive types of noise meters. They are typically used in professional measurements such as environmental noise (traffic noise, railway noise, aircraft noise), building acoustics, engineering measurements, or sound power.

  • Class 2

These are less expensive and still provide accurate measurements. Class 2 sound level meters are typically used in environments such as offices, classrooms, or general industrial facilities.

Types of noise level meters for occupational noise

Unless otherwise indicated in the measurement standard, class 2 sound level meters are generally accepted for workplace noise surveys.

Can I use my phone as a sound level meter?

Mobile applications can provide an approximate measurement of sound pressure, but they may not be accurate or reliable enough for professional use. They may not have the necessary features required by IEC 61672 for traceable calibration, making them unsuitable for use in professional settings. However, they can still be useful for initial noise surveys or personal monitoring of noise levels.

Professional sound level meters may use mobile applications as an extension of their user interface, but they do not rely on the mobile app to measure noise. They have their own hardware and software specifically designed to comply with international standards such as IEC 61672 for accurate and reliable noise measurements.

Are cheap decibel meters accurate?

If a decibel meter does not meet the standards set by IEC 61672, its accuracy and precision over time cannot be guaranteed. It’s important to remember that even small differences in decibel readings can have a big effect on sound pressure and volume. For example, a 3 dB increase in acoustic pressure means that sound energy is doubled, while a 6 dB represents a doubling of the sound pressure. So, if a decibel meter isn’t measuring sound levels correctly, the error can be big. 

IEC 61672 Sound Level Meters

The IEC 61672-1 is an international standard that specifies the performance criteria for professional sound pressure level meters. There are two performance categories specified by this standard: class 1 and class 2.

The following are the most essential components for sound level meters that comply with this standard:

  • linear operating range
  • frequency response
  • and temperature operating range

What's the difference between IEC 61672 Class 1 and Class 2 sound level meters?

In general class 1 sound level meters are more accurate and more expensive than Class 2 sound meters. 

Frequency range

Acceptance limits for variances in measured decibel levels at specific frequencies in the range of 10 Hz to 20 kHz are one of the most essential specifications of IEC 61672-1:

  • class 1 frequency range is from 16 Hz to 16 kHz,
  • class 2 frequency range is from 20 Hz to 8 kHz.

In practice, this suggests that class 2 noise level meters are not a good option for measuring higher frequencies (for example, cleaning machine parts using compressed air).

Linear operating range

The IEC 61672-1 criterion for the linear operating range is not overly rigorous in terms of decibels, as they demand only 60 dB dynamics between the lowest measured dB and the highest. Professional noise level meters typically offer a much wider operating range, for example, the SV 971A offers 110 dB from 27 dB to 137 dB. The word “linear” is the most important phrase in this context since it indicates that the precise measurements in the dB operating range fulfill frequency response requirements.

IEC 61672-1 Temperature operating range

The temperature operating range for a sound level meter that meets IEC 61672-1 should be from -10°C to 50°C for class 1 and 0°C to 40 °C for class 2. In practice, this implies that class 2 sound level meters are not appropriate for accurate measurements in areas where the temperature drops below 0°C (for example, food processing plants).

What is a frequency weighting?

By IEC 61672, frequency weighting is a difference between the frequency weighted signal indicated on the meter display and the corresponding level of a constant-amplitude sinusoidal input signal. 

Most sound level meters use A, C, and Z frequency weightings. The most commonly used is A-weighting, as it represents human hearing and is used for LAeq measurements. The C filter uses less attenuation on lower frequencies than A-weighting. For this reason, C-weighting is used to assess low frequencies in the signal by the difference between LCeq and LAeq levels. For the same reason, C-weighting is also used for peak sound level measurement. The Z-weighting has a flat frequency response from 10 Hz to 20 Hz and is often used for frequency spectrum measurement in octave bands. 

What is the difference between a sound level meter and a noise dosimeter? 

A noise dosimeter is a small sound level meter that is attached to a person’s clothes and is worn during the workday to measure noise exposure and noise dose. Following IEC 61252 noise dosimeters meet specifications for class 2 sound level meters.

What is the difference between sound exposure and noise exposure level?

The noise exposure level LEX is calculated by noise dosimeters on a basis of LAEQ that is normalized to 8 hours. The sound exposure level LAE is a time-averaged LAEQ during the averaged time interval normalized to 1s. 

Sound Level Meters Reviews

We’ll go through the finest Svantek professional sound level meters for classes 1 and 2 below. They’re all digital noise level meters, which means they convert noise levels into decibel readings on a screen in decibel units.

Top-of-the-line sound level meter

The SVAN 979 is the top-of-the-range class 1 integrating sound level meter. It has been on the market for more than ten years, indicating that its software is well established and stable. The meter is packed with a diverse set of features, making it ideal for a wide range of tasks. If you’re looking for a sound level meter to measure noise in extremely quiet places, this is the one to use since it measures down to 12 dBA! It also has an integrated program for conducting sound insulation measurements, including a signal generator that may generate pink noise and white noise. Furthermore, the meter can measure vibration by connecting the vibration sensor instead of the microphone.

The best performance price

If you’re on a budget, the SV 977 may be worth considering, which is a comparable model. Some of the features, such as the noise generator, are not included and others are optional, but they all impact on price.

The best class 1 sound level meter

The SV 971A is a new generation sound level meter, which explains why it’s smaller than the 979 and 977. The SV 971A is the best choice for individuals who just want to measure noise without vibrations. Because of the small size of the instrument, the display size is limited, but all noise data may be viewed on your smartphone or tablet’s screen thanks to the mobile app. The SV 971A is also the most affordable professional noise level meter.

Class 2 sound level meter

The SV 973 is a class 2 noise level meter, which means it’s an ideal tool for measuring noise levels in workplaces. It’s also an excellent meter for measuring sound levels in classrooms with options for the measurement of speech transmissibility and reverberation time. The class 2 designation indicates that the meter is intended to measure sound waves only in temperature conditions above  0° C and a limited frequency range to 10 kHz, although it is still a professional type of meter.

Sound level meter calibration

Sound level meters are used to measure sound pressure levels. They are important tools for environmental noise control, product design, and many other applications. To ensure accurate measurements, it is important to calibrate your sound meter regularly. In this section, we will discuss the process of calibrating a sound level meter and provide some tips on how to do it correctly.

What does the term "calibration" mean?

To verify the sound pressure level meter readings, a sinusoidal sound pressure level produced by a sound calibrator is used as a reference source in acoustical calibration. To calibrate the sound level meter, it must be adjusted to the level produced by the sound calibrator.

What is the difference between calibration check and calibration?

We’re talking about calibration with adjustment when the meter is adjusted to the calibrating signal. When no changes are required, the calibration check occurs (calibration without adjustment).

When should I calibrate and when should I check?

The calibration should generally be completed before taking a series of measurements. The calibration should be verified (without adjustment) after measurements to compare the readings before and after.

Periodic verification

Unless it is regulated by local standards, the sound level meter shall be verified in an accredited laboratory in intervals not exceeding 2 years.

What sound calibrator should I use for my sound level meter?

For class 1 noise level meters the calibrator shall conform to the class 1 specifications of IEC 60942. For class 2 noise level meters, the sound calibrator shall conform to either class 1 or class 2.

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