In the previous article “Acoustic pollution and Health” we defined what was sound, noise, what we understood as noise pollution and its repercussion on health. These definitions were important to enter into context and to develop this article. But first of all, we must differentiate that it is a noise emitter and receiver.
An Emitter can be any activity, infrastructure, equipment, machinery or component that generates noise pollution and is classified into 13 types: 1) Motor vehicles, 2) Railways, 3) Airplanes, 4) Road infrastructures, 5) Airport infrastructures, 6) Infrastructures , 7) Railway infrastructure, 8) Machinery and equipment, 9) Construction of buildings and infrastructure, 10) Industrial activities, 11) Commercial activities, 12) Sports, recreational or leisure activities and 13) Domestic activities.
As we can see, there are many types of noise emitters and, for each of the activities, there is a rigorous regulation (such as Law 37/2002 of November 17 of noise, Law 16/2002 of June 28 of protection against noise pollution, Decree 176/2009 of November 10, which approves the regulations of Law 16/2002, Ordinances regulating noise and vibrations, among others), which specifies the level of noise emission allowed, time slot, .. becoming punishable if not met.
Anyone person can be a Noise Receiver and the perception of this is different for each of us. It is very difficult to qualify objectively when a noise is annoying or pleasant because it is a subjective perception of each person and, it is for this reason, that noises are quantified when they are emitted or produced.
The noise level detected by the human ear varies between 0 and 120 decibels (dB), this last value known as “Pain threshold”, since at higher levels physical damage to the eardrum can occur. Next, we can see a graph of the quotidian noise scale (Fig. 1):
Figure 1. Graphic scale of the noise levels that we can find on a daily basis and how they can affect our health. Source: extreme data from the websites: https://sites.google.com/site/1285educacionartisticamusica/home/actividades i http://contaminacionacustica.net/efectos-de-la-contaminacion-acustica-sobre-la-salud/
Bequeathed at this point, we can ask ourselves how is noise measured? What devices do we have installed in our city to measure noise? What is done with the collected data? The noise monitoring sensors that we have installed at 11 points in our city are from the CESVA TA120 model (Fig. 2). These sensors measure noise continuously (24h / 7d) with great precision and are camouflaged with street furniture (lampposts, lights, tanks, advertising bullets,) and, therefore, if we go through the streets it will be difficult to see them if we do not know What are we looking for. It should be noted that these sensors are fixed, but what exactly does this mean? This means that, in order to function and send measurement data to the Sentilo platform, they must be permanently connected to the electricity grid and to a direct connection to the Internet using an Ethernet cable.
Figure 2. TA120 noise measurement device from the manufacturer CESVA, installed in the city of Terrassa. Source: Cesva (https://www.cesva.com/es/productos/sensores-terminales/TA120/).
Once presented the device and before explaining the operation of reading the noise in a certain place, we will make a small section on how the noise i is classified, which must be taken into account to make the decision of this.
In the city we can have 3 types of noise (Elvira, 2018):
- Continuous and stable noise
- Continuous and variable noise
- Short noise and impulsive noise (example: blows, loads, …)
The noise measure time is highly variable and depends on the type of noise that is to be measured. The easiest noise to measure is a continuous and stable one, since the measurement duration is between 15 and 60 seconds and, during this time, it must collect the entire noise cycle. For continuous and variable sounds, the measure time must include at least one cycle of noise, while for short and impulsive sounds the duration of the measurement must be as short as possible and, above all, representative.
As you can see, before carrying out the measurement, it is necessary to know the type of noise to analyse and the regulations to follow when making it (methodology, legislation, type of activity, location, type of device to be used, …) and it is not an easy task to do.
The 11 sensors that are distributed in the city are configured to carry out measurements of accumulated environmental noise per second and minute.
Currently, the main problem that we find in the analysis of the noise that the sensor captures is that the noise that it detects and sends to the Sentilo platform is compiled, that is, it doesn’t differentiate each of the noise sources that are in the street ( for example, the noise of the bus, people, cars, …) since the frequencies are not detected separately. This is a factor that we would like to study and we hope that the device that allows us to do so will be on the market soon.
- AJUNTAMENT DE TERRASSA (2020). Normativa [online]. Retrieved from: https://aoberta.terrassa.cat/normativa
- AJUNTAMENT DE TERRASSA (2020). Sentilo Terrassa. Plataforma d’interconnexió de sensors i actuadors de Terrassa [online]. Retrieved from: http://sentilo.terrassa.cat/sentilo-catalog-web/h
- CESVA (2020). TA120. Sensor de monitorización de ruido [online]. Retrieved from: https://www.cesva.com/es/productos/sensores-terminales/TA120/
- CONTAMINACIÓN ACÚSTICA. TODO SOBRE LA CONTAMINACIÓN ACÚSTICA (2020). Efectos de la contaminación acústica sobre la salud [online]. Retrieved from: http://contaminacionacustica.net/efectos-de-la-contaminacion-acustica-sobre-la-salud/