1,721,145 research outputs found
Recent advances in noise barriers testing, qualifying and standardisation
No full textThe standardization activity inside CEN (European Standardization Committee) is giving an important contribution to the definition of the technical characteristics of noise barriers and related devices; new test methods have been purposely developed and validated. Sound absorption and airborne sound insulation in a reverberant sound field (like inside tunnels or deep trenches) are tested in laboratory using optimized versions of the ISO 354 and ISO 140-3 standards. The same properties can also be measured in a direct sound field, e.g. in situ on free standing noise barriers, thanks to a new method based on an impulsive technique with the use of a deterministic test signal. A similar technique can also be applied to characterise sound diffraction of “added devices” which may be placed on the top of noise barriers. The principles of these methods are presented here together with real life results. Other standards dealing with non-acoustic performances (like mechanical resistance and fire reaction) and long term performances will be briefly presented, as they concern how to keep noise barriers and related devices performing correctly for many years. In the rail sector, new standards are in preparation about insertion loss and fatigue from dynamic loads due to passing trains. In the road sector, the existing standards make it possible to prepare a “declaration of conformity” of the device according to the European rules, which authorizes affixing the CE marking on products
Measurement of the sound-absorption coefficient in situ: The reflection method using periodic pseudo-random sequences of maximum length
No full textThe problem of measuring the sound-absorption coefficient in situ is approached in a systematic way, accounting for parasitic reflections and background noise. The basic reflection method is improved by using pseudo-random binary sequences of maximum length as the test signal. The measurement procedure is orientated towards digital processing techniques and uses the advantages of modern instruments. The inherent cross-correlation process greatly improves the noise immunity. The relationship between the loudspeaker characteristics and the sample size is clarified. The use of a non-rectangular analysis window is suggested. The proposed method was tested in a normally furnished room using portable instruments; the normal-incidence results are in good agreement with values measured using the conventional Kundt's tube method. © 1993
Sull’incertezza di misura in acustica edilizia
No full textQuesto lavoro evidenzia che anche in acustica edilizia per fornire risultati affidabili, cioè di qualità, bisogna considerare l’incertezza di misura. Infatti l’incertezza può essere ridotta al minimo, compatibilmente con lo stato dell’arte, ma non può mai essere eliminata. Quindi non dichiarare l’incertezza significa non potere dimostrare l’attendibilità del risultato. Le norme esistenti permettono di stimare l’incertezza di misura in maniera tecnicamente corretta, sia in opera che in laboratorio. Naturalmente bisogna familiarizzarsi con i concetti di base: incertezza tipo ed estesa, livello di fiducia e via dicendo. Ciò richiede un certo sforzo, ma è inevitabile, se non altro perché nel confronto di una grandezza misurata con un valore limite, l’incertezza determina l’attendibilità del risultato. A questo proposito si mostra che sono teoricamente possibili diverse regole di decisione, che vanno scelte considerando attentamente il fine della valutazione
Measurement of sound reflection and sound insulation of installed noise barriers using the SOPRANOISE quick method
No full textThis paper presents the preliminary results of a study on the new possibilities emerging from the analysis of measurements on installed noise barriers following the quick method designed in the frame of the SOPRANOISE project. Measurements of sound reflection and sound insulation were done in laboratory on a full-scale acoustic barrier and on an acoustic barrier installed along the Brennero motorway in northern Italy. The measurements were carried out using the SOPRANOISE quick system device, designed and engineered to provide a fast and lightweight version of the Adrienne method (i.e., EN 1793-5 and EN 1793-6), and then checked by applying the standardized Adrienne method, using instrumentation and procedures validated during the round-robin test performed in the frame of the QUIESST project. The preliminary results of the measurements are presented
Experimental verification of a short method for the determination of the acoustical insulation index of party walls
No full textThe results are presented of experimental work, still in progress at the University of Bologna, aiming to verify the feasibility and reproducibility of a short test method for estimating the sound reduction index of a party wall, according to the ISO proposal (ISO TC 43/SC2/WG10). The method is intended as a quick test to be carried out with reduced instrumentation, during building construction. It is based upon the determination of the A-weighted sound level difference between adjacent rooms, DA. This difference is compared here with the more usual indices (see ISO 140 and 717), and empirical correlations are found that are well correlated to experimental data and so permit forecasting which is more than satisfactory for a survey check method. The empirical correlation equations are in good agreement with the proposed ISO table, which is therefore confirmed, notwithstanding the differences between British and Italian data. A deeper insight into the measured data suggests that receiving room reverberation time measurement is one of the main causes of variance; in order to solve this problem work hypotheses are put forward which do not require the use of absorbing packs. © 1989
A Low-Cost System for Quick Measurements on Noise Barriers in Situ
Full text linkThis paper describes the development of a low-cost device for measuring the acoustic intrinsic characteristics of noise barriers. The system is based on the Teensy 4.1 microcontroller combined with a few other components. The measurements are carried out using a vertical linear microphone antenna housing 6 microphones and a lightweight loudspeaker, wireless connected to the main unit. Both the main system unit and the amplified loudspeaker are powered from normal 5 V USB battery packs, which are easily rechargeable and interchangeable. The system measures 6 impulse responses using an MLS signal and performs a series of calculations and frequency analyses to characterize the device under test, following a simplified version of the European standards EN 1793-5 and EN 1793-6 (commonly referred to as the ’Adrienne method’). One measurement takes few minutes, obtaining results comparable to those obtained with the Adrienne method, which requires a more complicated and heavy measuring equipment and is much more expensive and time consuming
Caratteristiche acustiche interne di ambienti confinati. La UNI 11532 diventa una ‘serie’
No full textNegli ultimi anni, l'attenzione al comfort acustico negli ambienti di vita ha assunto un ruolo significativo in ambito internazionale come risposta ad un’esigenza oggettiva. Ne sono un esempio le recenti normative straniere che forniscono valori di riferimento per molteplici destinazioni d’uso quali aule scolastiche, luoghi di ristorazione, uffici e cosi via.
A livello nazionale, con l’emanazione del Decreto 11 Gennaio 2017 del Ministero dell’ambiente e della tutela del territorio e del mare – Adozione dei criteri ambientali minimi per gli arredi per interni, per l’edilizia e per i prodotti tessili ovvero dei Criteri ambientali minimi (C.A.M.) il legislatore ha riconosciuto l’importanza di questi criteri da adottarsi per gli edifici pubblici. Tre i punti fondamentali sanciti nel Decreto: distinzione tra edifici pubblici e privati; differenziazione tra isolamento acustico e comfort acustico; richiamo in un decreto con valore cogente delle norme tecniche UNI.
Per l’acustica interna di singoli ambienti, il riferimento normativo è la UNI 11532:2014; da qui l’esigenza di rivedere la norma al fine di rispondere pienamente alle attese legislative. Infatti Bandi e Gare d’Appalto Pubblici faranno riferimento ai C.A.M. e di conseguenza alla suddetta norma che pertanto dovrà avere obiettivi chiari, specifici metodi di previsione, specifici metodi di verifica e chiari elementi oggetto di verifica, ma soprattutto dovrà essere un riferimento per molteplici settori in cui le persone sono impegnate a comunicare, ascoltando o parlando, per lavoro o piacere.
Date le molteplici tipologie di ambienti coinvolti, si è reso necessario far evolvere la UNI 11532 in un pacchetto di norme che potessero, in modo più dettagliato, rispondere alle diverse esigenze, individuando obiettivi ad hoc e descrittori acustici rispondenti
A European inter-laboratory test of airflow resistivity measurements
No full textThis article presents and analyses the results of an Inter-Laboratory Test (ILT) of airflow resistivity measurements according to the ISO 9053 standard. The main result of the ILT is the determination of the repeatability and reproducibility standard deviation values typical of these measurements, for the first time since the ISO 9053 publication in 1991. Ten European laboratories took part in the ILT project; two melamine foam sheets of different thickness, taken from the same factory batch, were sent to each laboratory. The laboratories cut the test samples and carried out measurements in repeatability conditions, either on a single sample either on different samples, in order to take into account also the influence of the sample cutting and non-homogeneity of the foam. The data show that most of the laboratories have a good internal repeatability, particularly for single sample measurements. The overall reproducibility is not so good, mainly due to systematic deviations inherent in the current laboratory practice. Measurements conducted by some laboratories using different methods, in order to verify their effective equivalence, are also reported. Finally, remarks on the current measurement procedures and proposals of amendments to the ISO 9053 standard are presented
Report on the AIA-UNI symposium “The evolution of technical standards in acoustics: latest updates”
No full textIl giorno 20 marzo 2025 si è tenuto il simposio AIA-UNI "L'evoluzione della normativa tecnica in acustica: ultimi aggiornamenti" presso la sede UNI di Milano. Il simposio è stato organizzato congiuntamente da AIA e UNI con lo scopo specifico di aggiornare sui temi caldi della normativa tecnica italiana chi si occupa di acustica e in particolar modo i soci AIA e i soci UNI. In questo articolo si propone un resoconto delle attività scientifiche che si sono tenute durante il Simposio
Sound insulation measurements on noise barriers across their entire extension: a preliminary study
No full textEN 1793-6 allows measuring the in-situ sound insulation of installed noise barriers at selected
positions, but it would be desirable to check the quality of the installation or the decrease in
performance over time over the whole length of a noise barrier. For this purpose it is necessary
to carry out measurements along the entire extension of the noise barrier and not just at few
positions taken as representative. This work presents a preliminary study of a quick method
for evaluating airborne sound insulation along the entire length of a noise barrier and finding weak points, like assembly errors. Preliminary measurements were made by moving in the horizontal direction a linear antenna of microphones, kept vertical, along the entire width of the barrier in 0.25 m steps. On the opposite side of the barrier (noise source side) a loudspeaker was held in axis with the microphones, at fixed height, for each step. The entire surface of a 9 m wide, 4 m high sample barrier was analysed. Processing the measured impulse responses
between the loudspeaker and the microphones, global images of the local airborne sound insulation can be obtained in each frequency band
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