Cirrus Research plc

What are the 4 Different Types of Noise?

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Courtesy of Cirrus Research plc

Noise comes in all shapes, sizes and sounds. It’s part of our everyday lives but before you can accurately measure it, you need to know what the different types of noise are. Here’s my advice.

Whether it’s the innocent beep, a plane flying overhead or heavy machinery in your workplace, you can’t escape noise. If want to accurately measure and analysis noise, you need to understand the difference between the difference types of noise first so you can choose the right equipment and parameters.

First Things First – What is Noise?

Noise is defined as any unwanted sound that you don’t need or want to hear.

Our ears are excellent at telling us what noise is. Most commonly, noise is an annoying tone that causes mild to major discomfort/irritation. These tones pierce through the background noise that accompanies our lives.

When it comes to measuring the different types of noise, we usually want to replicate the performance of the human ear to get an accurate representation of its impact. That’s why we use the A-Weighting Frequency, which is much more sensitive between the 500 Hz and 6 kHz range. Learn more about A, C and Z Frequency Weightings.

The 4 Types of Noise


Here’s a breakdown for the different types of noise that affect us all.

1. Continuous Noise

Continuous noise is what it says on the tin. It’s noise that is produced continuously by machinery that keeps running without interruption. This could come from factory equipment, heating or ventilation systems.

You can measure continuous noise for just a few minutes with a sound level meter to get a sufficient representation of the noise level. If you want to analyse the noise further, you need to look for a sound level meter with Octave Band analysis. This breaks down the noise into its separate frequencies and tells you exactly what frequency is causing the noise. You might even want to break down the noise into 1:3 octave bands which can give even more detail about the frequency content of the noise.

2. Intermittent Noise

Intermittent noise is a noise level that increases and decreases rapidly. This might be a freight train passing by, factory equipment that operates in cycles or aircraft overhead.

You measure intermittent noise in a similar way to continuous noise with a sound level meter. However, you also need to note the duration of each occurrence and the time between each one. To gain a more reliable estimate of the noise level, you should measure over multiple occurrences to calculate an average. If you’re using an Integrating-Averaging sound level meter, this will make the calculation for you and present this in terms of an LAeq.

3. Impulsive Noise

Impulsive noise is most commonly associated with the construction and demolition industry. This sudden burst of noise can startle you by its fast and surprising nature. Impulsive noises are commonly created by explosions or construction equipment such as pile drivers.

To measure impulsive noise, you will need a sound level meter or a personal noise dosimeter that can calculate Peak values.

Don’t forget that even in an environment that is generally quiet, a single very loud noise can cause hearing damage and this is why it’s important to measure Peak levels alongside the average or Leq value. In most applications, Peak will be measured using C-weighting so you should make sure that your sound level meter provides this.

4. Low Frequency Noise

Low frequency noise makes up part of the fabric of our daily soundscape. Whether it’s the low background humming from power plants or the roaring of large diesel engines, we’re exposed to low frequency noise constantly. This is also the hardest type of noise to reduce at source, so it can easily spread for miles around.

For low frequency noise, you should be using a sound level meter with Third Octave Band analysis so you can analyse the low frequencies that make up the noise. You may also need to look at the C-Weighted measurements and compare this to the A-weighted measurements as this can show how much low frequency noise is present. Find out more about the different frequency weightings.

If monitoring is taking place outside over a longer period, you might want to consider an environmental noise monitoring kit.

Ready? Start Measuring

So, there you have it. The 4 different types of noise to consider before you voyage into the world of noise monitoring. When searching for the right equipment to use, ask yourself “what do I need to measure?” and it’ll make your search that much easier. Alternatively, ask the Noise Experts at Cirrus Research or use our online Product Selector. We can recommend the best instruments for you to use based on your requirements.

Until next time, friends.

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