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      • Published 24 Jan 2023
      • Last Modified 31 May 2024
    • 5 min

    How to Measure Decibels

    Understanding how to measure decibels accurately and efficiently is essential. Learn more in our guide.

    Published March 2022

    Sound measurement can be essential for health and safety purposes, so an accurate way to record decibel (dB) ratings is often needed. Typically, devices such as sound level meters are used for this purpose.

    Sometimes referred to as decibel meters, a sound meter will take acoustic measurements in an environment. They achieve this with a pre-calibrated microphone that then electronically analyses and displays the sound level with either a digital or analogue style meter.

    RS Pro provides a range of sound level meters to suit a variety of applications and environments.

    How are Sound Levels Measured?

    Sound Level Meter

    Noise measurement is typically measured in Decibels (dB) which is the standardised way of measuring loudness. The reason Decibels are so well suited to this is that the Decibel scale is a logarithmic scale that is closer to how the human ear responds to loudness. As such, it creates a more relatable scale for loudness in health and safety.

    When considering how to measure noise levels, the appropriate tools are needed. Sound meters work with a microphone that measures sound pressure in an environment and calculates it into a decibel reading. Because of this, sound level meters are sometimes called sound pressure level readers.

    How to Measure Sound

    A variety of factors may have a bearing on perceived and actual levels of sound. The period of exposure, frequencies (or pitches), and the environment will all have some impact. Sound intensity (otherwise referred to as sound power or pressure) is measured in decibels (dB). You should be aware that sound is measured in logarithmic terms, relating to the physical sensation felt upon hearing. A gradual increase in sound level will result in greatly increased intensity and perceived loudness.

    Sound levels may also be measured in terms of weighted decibels (dBA). Such measurement is directly associated with the impact on hearing health. It relates specifically to the intensity of sound and impact on the human ear. Small increases in the dBA level can have a significant impact on your hearing.

    There will be a greater risk of hearing damage on exposure to:

    • 85 dBA for a period of at least 8 hours
    • 100 dBA for at least 14 minutes
    • 110 dBA for at least 2 minutes

    The frequency of sound is measured in terms of the number of sound vibrations per second. A person with optimum ear health can hear sounds of frequencies between 20 Hertz and 20,000 Hertz. There are various types of electronic equipment that can be used for the purpose of measuring sound levels in dB and dBA.

    Where are Sound Level Meters Used?

    Measuring decibels can be useful for multiple applications, whether it's to measure the background noise of an environment or the noise levels of specific machinery. Loud or sustained noise in a work environment can lead to hearing damage and even potential hearing loss in staff. Additionally, unacceptable levels of background noise in environments have been proven to have a detrimental effect on mental health and the quality of life. With this in mind, measuring decibel levels is an extremely important way of deducing whether an environment is suitable for people.

    A noise meter might be used by a council or local authority to make sure event or domestic noises are within acceptable and legal limits, or by private businesses to make sure noise exposure on a shop or factory floor is safe for workers.

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    What is a Safe Decibel Level?

    When considering how to measure decibels of noise, it’s important to know what noise levels are deemed ‘safe’ or appropriate to an environment. Typically, 50 dB is considered a moderately noisy environment, with 85 dB considered to be very noisy. Levels above that are considered painful to the human ear and potentially dangerous.

    Safe or appropriate Decibel levels may vary from country to country and sometimes differ between local authorities. For example, 2005 UK regulations state that work environments where noise levels reach 85 dB must supply their employees with hearing protection.

    Be sure to thoroughly research the local compliance and regulations in your workplace.


    How Do I Know My Noise Meter is Accurate?

    When considering how to measure decibels of sound, a reliable and well-calibrated tool is essential. RS PRO takes pride in delivering appropriate tools for many applications, as well as the support and information you need to make the right choice.

    We also offer our RS Calibration service, ensuring your instruments are accurate and compliant to the applicable standards.

    Are Analogue or Digital Displays Better?

    Typically, analogue displays give you a quicker idea of where current noise levels stand in relation to a visible range. As such, for a fast and intuitive idea of the noise levels around you, analogue displays are very convenient. However, digital displays will typically give you a much clearer and exact idea of the noise levels being read and are probably more useful when specific and accurate readings are required.

    Where to Next?

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