About Noise Monitoring

Noise measurements are often done with the purpose to know what the levels are by measuring environmental noise. Environmental noise can be caused by traffic (cars, trains, motorbikes, airplanes), industrial buildings or sites, entertainment venues or neighborhood noise.

They all make sound and sound starts to be noise once we perceive it as nuisance or worse. Noise litteraly means ‘unwanted sound’.

According to the WHO (World Health Organization) noise is the worst environmental nuisance only after air pollution. There is a lot of research that proves that noise is much more than nuisance, it’s actually very bad for your health, during daytime for your hearing and during night time for your peace of mind. Enduring noise during your sleep will increase your stress levels and of course if you’re not well rested you risk making errors in the daytime.

Luckily that noise induced hearing loss is 100% preventable, just don’t expose yourself to loud noises voluntarily, wear ear mufflers if you’re working in a loud and noisy environment (> 80 dB(A)), also disco’s are bad, use earplugs to protect yourself !

Many countries have environmental agencies that will follow up all noise complaints but sometimes they are very busy so you could have to wait weeks or months before they will actually assess your situation and measure the noise. In many developing countries regulations for noise protection are none existing or not enforced. Here comes the need to take the helm in your own hands.

The first step (after recognizing that you endure noise nuisance) is to quantify the noise levels. Noise monitoring is a very good, easy to use and reliable method for this. You can install a noise monitor at the place that gets the highest noise levels. The noise monitor will register the noise 24/7 and can even send you notifications if a certain sound level is exceeded. You can look back in the history which days there were exceedings for the maximum allowed soundlevels.

With the results of a few days or weeks, you can print the results and give to the local authorities. They will know and acknowledge that our SpotNoise monitors are calibrated so the registered sound levels are correct. Also, with each instance that the noise levels are exceeded, an automatic recording will be started so you can listen later if the noise was indeed from the noise nuisance course of maybe just from a passing car or barking dog.

Here below is a list with some machines and situations and the sound levels they produce (measured at 1 meter distance):

How loud is too loud?
Source osha.gov

In your bedroom the WHO recommends a sound level not higher than 30 dB(A) with peak levels not higher than Lmax 45 dB(A) but even lower noise levels could be annoying depending the characteristics of the noise.

Here below we show you another table from the WHO with recommended maximum noise levels for various buildings:

Table 1: Guideline values for community noise in specific environments.

Specific environmentCritical health effect(s)LAeq
Time base
Outdoor living areaSerious annoyance, daytime and evening
Moderate annoyance, daytime and evening
Dwelling, indoors
Inside bedrooms
Speech intelligibility & moderate annoyance, daytime & evening
Sleep disturbance, night-time
Outside bedroomsSleep disturbance, window open (outdoor values)45860
School class rooms & pre-schools, indoorsSpeech intelligibility, disturbance of information extraction, message communication35during class
Pre-school bedrooms, indoorSleep disturbance30sleeping-time45
School, playground outdoorAnnoyance (external source)55during play
Hospital, ward rooms, indoorsSleep disturbance, night-time
Sleep disturbance, daytime and evenings
Hospitals, treatment rooms, indoorsInterference with rest and recovery#1  
Industrial, commercial shopping and traffic areas, indoors and outdoorsHearing impairment7024110
Ceremonies, festivals and entertainment eventsHearing impairment (patrons:<5 times/year)1004110
Public addresses, indoors and outdoorsHearing impairment851110
Music and other sounds through headphones/ earphonesHearing impairment (free-field value)85 #41110
Impulse sounds from toys, fireworks and firearmsHearing impairment (adults)
Hearing impairment (children)
140 #2
120 #2
Outdoors in parkland and conservations areasDisruption of tranquillity#3  
WHO guideline for community noise in specific environments

#1: As low as possible.
#2: Peak sound pressure (not LAF, max) measured 100 mm from the ear.
#3: Existing quiet outdoor areas should be preserved and the ratio of intruding noise to natural background sound should be kept low.
#4: Under headphones, adapted to free-field values.

Much research has been done for example in hospitals, the recovery time of a patient can be halved if the noise levels are lowered by 10 dB(A)!

Schools as well, a high STI value (speech intelligibility index) in classrooms (means easy to understand the teacher in any student location in the class) will ensure that all students have equal chance to succeed. Many classrooms, however, have areas with poor speech intelligibility hence many students will miss out critical information from the teacher. Let alone if a student is hearing impaired.

In many cases, careful planning and respecting your environment can prevent noise nuisance, let’s be kind to each other and don’t create unnecessary noise. Let’s create more awareness about noise and the dangers so everybody can help to make this world a bit quieter!

If you have any questions about a noise nuisance situation, please fill in our contact form, our engineers are happy to consult you (initial consult free !).

Noise mapping vs Noise monitoring

As soon as you are experiencing noise nuisance from a noise source (be it road-noise, rail noise, aircraft noise, industrial noise, entertainment noise etc.) noise mapping doesn’t satisfy. Noise mapping is very good and reliable for city planning and to locate hotspots in cities which need attention for noise mitigation. Another advantage from noise mapping and noise prediction software (such as SoundPLAN) is that you can experiment with for example diverting a road or changing traffic flows to alter the noise levels without having to implement it first. In Environmental Impact Studies (before starting a project) there is always a noise prediction required, once again, a perfect situation to use noise mapping and noise prediction software.

However, noise maps calculate average values and they are not able to predict noise coming from installations or events with irregular (unpredictable) activity patterns. In these cases only real time noise monitoring can show and register what the noise nuisance really is and how the noise pattern changes over time, Regulations from governments or cities typically will define equivalent (averaged) noise values as well as maximum noise levels. Noise monitoring will register all needed values to be able to assess the compliance of the noise regulations.

Sometimes the local authorities will install noise monitors and share the information online so citizens can see what is happening in real values rather than only subjective endure the noise nuisance. Typically, noise complaints decrease once noise monitors are being installed and data is shared to the public.

In many cases, however, authorities cannot always follow up with every noise complaint or noise monitoring request. Here SpotNoise Residential is the best solution. Accurate, very easy to install, measuring and registering all noise levels and details up to 1 year online. The SpotNoise Residential noise monitoring is weatherproof and just needs wifi and powersupply to register the noise.

All measured values are available online (so you can share with the authorities or with the noise polluter) and can also be downloaded in csv format for further analyzing if required.

SpotNoise helping to create noise awareness and noise registration so authorities can enforce regulations better and faster and create quiet living spaces for people to be able to relax and have a sound sleep sound at their residences.

IEC61672 vs SpotNoise monitoring

If you need to be 100% accurate in the noise levels that are being registered (i.e. to be used in court), then most likely the court will require your noise monitoring equipment to comply with IEC61672, this is the standard for ‘Electroacoustics – sound level meters’, typically only issued by top-level institutions such as the PTB in Germany (the German National Meteorological Institute). Within the standard there are 2 classifications, class 1 and class 2 (also referred to as Type 1 and Type 2) meters.

Class 1 has an accuracy of +/- 1.9 decibel, Class 2 has an accuracy of +/- 2.2 decibel.

The complete monitoring station has to be a the same level of accuracy, not only the sound level meter but also the measurement microphone. An official sound measurement microphone Class 1 can cost up to USD 1500 !

Since the introduction of MEMS (digital) microphones, noise monitoring has become much more affordable. These very stable digital microphones don’t comply with IEC61672 as they cannot be exposed to an electrostatical test, apart from this, they fully comply to Class 1 or even higher accuracy rates.

This implicates that if you don’t need your measurements to go to court you can fully rely on SpotNoise Residential monitor well within the range of Class 2 sound level meters (SpotNoise Residential’s accuracy is +/- 2.0 dB). Even though a court will most certainly look at noise levels measured with SpotNoise equipment and if the maximum values are clearly exceeded (> 5dB) they will acknowledge something is wrong with the noise situation and will investigate further !

Online vs offline noise monitoring

Offline noise monitoring is the cheapest way, you just install a noise monitor on a location and on given times you go there to download the data and post-process it. In many cases, however (as in the previous example where authorities want to share realtime noise values) online accessibility is required. Especially in the case that you want to be notified automatically once a preset value is exceeded, you will have to use online noise monitoring. SpotNoise’s systems all use wifi to connect to our servers which will display all values and keep the data online for 1 year (standard). You can set at which level you want to receive a notification (email/messenger) so you can react instantly. Online monitoring is not only used by plaintiffs. The noise polluter more and more is setting up noise monitoring stations for example on the boundary of his factory and will act if sound levels are too high, actions may be temporary shutting down a machine or just simply closing a door that somebody forgot to close.

Real Case Studies

Some examples where noise monitoring is often used and in many countries is mandatory:

  • airports, roads, railways, ports
  • industry (individual factories or zoned industrial areas)
  • wind farms (especially for low-frequency noise)
  • Leisure noise (outdoor concerts, bars/pubs/disco’s, outdoor cinema’s, sporting events, shooting range etc.)