ACOUSTIC ACCORDING TO PSE TECHNOLOGIES
Environmental noise pollution has now reached high thresholds, which have led the legislator to issue a series of precise provisions, aimed at regulating the sector and limiting the nuisance generated by noise and the consequent damage to human activity. It has been ascertained that these consequences for humans are not limited only to the auditory system, but involve most organs and systems, starting with the autonomic nervous system. In some cases, however, it is particularly difficult to act on the source of noise pollution and therefore it can be useful, to reduce the nuisance within the threshold values acceptable, intervene by creating sufficient acoustic insulation in areas of rest, work or more generally of daily life. Environmental acoustic interventions are essentially divided into two categories: – environmental reclamation and/or correction, in cases of excessive internal noise generated for example by machinery or equipment; – acoustic insulation, through the use of partition walls, false walls and false ceilings suitably designed to limit the transmission of noise from the outside to the inside in the case of noise coming from the street or between one room and another in the case of different lodgings, rooms hotels, cinemas, etc.
Noise Reduction NR represents the difference in decibels of the noise levels measured in the source room and in the receiving room. Acoustic insulation means interventions aimed at limiting the transmission of noise between one room and another.So if our neighbors disturb us or if, on the other hand, we disturb our neighbors with our activities, in this case we need soundproofing. Acoustic insulation is obtained by creating counter-walls or partition walls (usually in multilayer plasterboard coupled with an Isolmant type barrier) a floating floor decoupled from the existing screed and a ceiling suspended on elastic clips. It is therefore a rather complex and delicate intervention, certainly more demanding than placing sound-absorbing panels on the walls. Being a much more complex intervention, you must be clear that soundproofing requires a certain budget.
By acoustic treatment we mean all those interventions aimed at controlling and improving the acoustics of a room. We talk about acoustic treatment for environments dedicated to music such as control rooms, recording studios, rehearsal rooms, auditoriums, home theaters, but acoustic treatment is also necessary in cases where it is necessary to increase the acoustic comfort of rooms such as restaurants, schools , public places etc. in which it is necessary to make the sound signal reach the entire area intended for the public as clearly as possible, in a balanced and uniform way. The main objectives of the acoustic treatment are to control the reflections of the room, the resonances of the room, limit the reverberation time and in general all the acoustic problems typical of closed environments.
Soundproofing and sound absorption are two very different concepts. The soundproofing interventions have the purpose of minimizing the transmission of the noise between two rooms and therefore make sure that the noise produced in one room is not heard in the adjacent room.
Acoustic insulation and soundproofing power
There are two quantities that define the capacity of one in a different way structure to reduce airborne noise: acoustic insulation and soundproofing power. Where: L1 sound pressure level in the emitting environment L2 sound pressure level in the receiving environment
Sound absorption interventions have the purpose of controlling the reflection of sounds on the walls of a room and therefore adapting, according to one’s needs, the reverberation inside the room in which the noise is generated.
Acoustic insulation and soundproofing power
Reverberation is an acoustic phenomenon linked to the reflection of the sound wave from an obstacle placed in front of the sound source. The possibility of calculating the distribution of sound energy within an environment is very important in order to be able to deal with the acoustic problems that arise in certain categories of premises.
This quantity is in fact closely correlated with the “sound” of the room, understood as the ability to make the sound energy emitted by a source persist, to a greater or lesser extent. The reverberation time is linked, through Sabine’s formula, to the volume of the room and to the amount of sound absorption present in it. Depending on the destination and capacity of the room (which in turn determines its volume), the literature reports optimal values, understood as results to be achieved in order to obtain listening conditions which, based on functional and artistic evaluations, are deemed acceptable.
For correct acoustic testing of buildings, which complies with the relative DPCM of 12/5/97, 3 instruments are compulsorily used such as: the DODECAHEDRON, the SOUND METER and the TRAMPLING MACHINE. The law requires compliance with the acoustic requirements of the DPCM 5/12/97 not only in the planning phase but in reality, on site. The decree DOES NOT OBLIGATE you to carry out acoustic tests on site, but it does require that the acoustic requirements be met when the work is completed. All measurements of facade insulation, sound insulation of walls and slabs, foot traffic must be carried out with the premises in the state in which they are found at the time of the inspection, with the normal furnishings (furniture, carpets, curtains, etc.). There is no reason to empty the rooms of the furniture because the influence of the different reverberation time is taken into account through the correction prescribed by the UNI standards.The furniture (libraries, “wall” cabinets or large cabinets), in compliance with the separation wall between apartments, increase the soundproofing power. In these cases, when the measurement is critical, i.e. equal to or slightly more than the 50 dB limit value, the increase in sound insulation must be taken into account in order to be able to decide whether or not the wall complies with the legal limit. Certainly if the result was already lower than the limit, with 49 dB, and if the furniture were removed, the result would be even more insufficient.