What the research says
Experimental studies conducted in university and school settings – one of the main references is the RANCH project (Road Traffic and Aircraft Noise Exposure and Children’s Cognition and Health), coordinated by University College London and published on The Lancet And Journal of Environmental Psychology in the early 2000s, then taken up again in many subsequent meta-analyses – have shown that prolonged exposure to continuous background noise leads to a reduction in attentional performance and working memory, with an increase in cognitive fatigue, even in the absence of a conscious perception of disturbance.
The World Health Organization guidelines indicate, for residential environments, reference values equal to 55 dB(A) during daytime hours, with lower thresholds recommended for the night. These values do not just represent comfort limits, but thresholds beyond which the risks to psychophysical health increase.
Sound absorption and sound insulation: two complementary strategies
In light of the effects of noise on the human organism, the acoustic project takes on a central role in the quality of living. In this context it is essential to distinguish between sound absorption and sound insulation, two different but closely interconnected approaches.
Sound absorption concerns the internal acoustic behavior of an environment. Sound-absorbing materials and surfaces reduce reflected sound energy, controlling reverberation time and improving speech clarity. An excessively reverberant environment generates perceptual confusion, forces the brain to make a continuous decoding effort and increases mental fatigue. Acoustic false ceilings, wall panels, porous surfaces and solutions integrated into the furniture allow you to shape the sound field and create more stable and comfortable listening conditions.
Sound insulation, on the other hand, concerns the ability of building structures to prevent the transmission of sound between adjacent rooms or from the outside to the inside. Layered walls, correctly designed floors, mass-spring-mass systems, attention to construction details and acoustic continuity are essential elements to guarantee insulation from airborne and footfall noise. Good sound insulation protects privacy, reduces sound interference and contributes to the perception of safety and control of the environment.
An effective acoustic design must therefore integrate both strategies: absorb sound where internal quality is needed and isolate where functional separation is needed.
Italian regulatory framework: mandatory and non-mandatory measurements
In Italy, the main reference for the acoustic performance of buildings is the Prime Ministerial Decree of 5 December 1997, which defines the passive acoustic requirements in terms of:
- insulation against airborne noise between rooms;
- insulation against foot traffic noise;
- noise level of the systems;
- facade acoustic insulation.
This is accompanied by UNI 11367, which introduces the concept of acoustic classification of the building, allowing the attribution of a performance class on the basis of on-site measurements. The standard represents a fundamental tool for evaluating the overall acoustic quality and for objectively communicating the performance of a building.
The UNI EN ISO 16283 and UNI EN ISO 717 standards regulate the methods of measuring and evaluating acoustic insulation, guaranteeing uniformity, repeatability and comparability of the results.
On-site detection and measurement techniques
The verification of acoustic comfort requires instrumental measurements carried out according to standardized procedures. The main detection techniques include:
- the measurement of reverberation time, fundamental for evaluating the effectiveness of sound absorption and the internal acoustic behavior of environments;
- the measurement of the apparent acoustic insulation between rooms, carried out on site to verify the real performance of the structures;
- the measurement of sound pressure levels and their spectral analysis, useful for identifying specific critical issues linked to certain frequency bands.
Italian and European standards establish rigorous criteria for test conditions, instrumentation and data processing, making on-site measurement an essential tool not only for control, but also for design. It being understood that the Prime Ministerial Decree of 5 December 1997 defines the requirements, but does not impose instrumental acoustic testing as a mandatory final act.
In sensitive buildings, however, such as schools, kindergartens, hospitals, RSAs, healthcare buildings, acoustic testing is often required by regional regulations, public specifications or as a condition of functional usability. The register changes, however, if it is intended to declare an acoustic quality class of the building, as required by UNI 11367. Here the instrumental verification on site does not represent an optional choice, but a necessary, binding step. The standard, in fact, allows the attribution of the acoustic class exclusively on the basis of real acoustic measurements, carried out according to the procedures defined by UNI EN ISO 16283.
It is clear, therefore, that acoustic comfort is a structural component of living well-being rather than an accessory parameter. Managing sound means reducing environmental stress that is often underestimated, improving the quality of life and designing buildings that are truly health-oriented. From an integrated design perspective, sound effectively becomes a design material, capable of profoundly influencing the experience of built space.
