1,720,972 research outputs found
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
Impedance tube measurements on the denorms round robin test material samples
Full text linkThe DENORMS Round Robin Test aims to study and improve the techniques used to determine the sound absorption coefficient of materials. Within this framework, samples taken from the same batch have been tested in both reverberation room and impedance tube. The latter technique presents some challenges in that the results may strongly depend on the specimen preparation and set-up. The purpose of this paper is to present the results obtained in custom-made impedance tube for the RRT set of materials. The tests have been carried out using a four-microphone impedance tube, according to the method outlined in the ASTM E2611-09 standard. The results obtained for the different parameters provided by the test, in particular the sound absorption coefficient and the sound transmission loss, are taken into account and discussed
Principles at the basis of the denorms round robin test on the low frequency sound absorption measurements in reverberation rooms and impedance tube
Full text linkIn recent years low frequency measurements in building and room acoustics fields gained attention. Moreover the low frequency sound absorption coefficient (below 100 Hz) has always been difficult to determine and the results coming from different laboratories cannot always be compared. This paper describes the principles at the basis of the round robin test carried out in the framework of the DENORMS cost action (Designs for Noise Reducing Materials and Structures). The same samples have been measured in reverberation rooms and in impedance tube by the different laboratories participating to the Round Robin Test.status: Accepte
On the uncertainty of sound reduction index measurements from inter-laboratory tests
No full textTest reports of building acoustics measurements cannot be considered complete without declaring the associated uncertainty. Two dominant methods exist for calculating the un-certainty, i.e. the empirical approach, standardized in ISO 5725, and the modelling ap-proach, standardized in ISO/IEC Guide 98-3. The state of the art is so that this uncertainty must be assessed using the standard deviation of reproducibility obtained from multiple Inter-Laboratory Tests (ILTs), whose average values are standardized in ISO 12999-1. However, here three standard deviations are given: the usual repeatability and reproduci-bility standard deviations and an additional new standard deviation R95, neither defined nor used before. In the paper, it is shown that R95 causes an over-coverage in the fre-quentist sense, while the natural choice is the reproducibility standard deviation, both for laboratory and field measurements. Moreover, it is remarked that for products for which a specific inter-laboratory test (test code) already exists, a smaller uncertainty can be used, and this may produce an unbalanced situation on the market
On the reasons of the revision of ISO 16283-3: first results of measurement campaign on loudspeakers
No full textThe facade sound insulation measurements method is
standardized in ISO 16283-3, which is being revised.
The reasons for the revision are multiple. First, the
dimensions and volumes included in the standard could not
be sufficient to consider some higher volumes like openplan
offices and classrooms. Second, the instructions for
bigger façades are not sufficiently clear in particular
situations. Therefore, an annex like the one in the first and
second parts of the standard is required. Third, it was
argued that the preferred method to estimate the global
sound insulation of a façade would be the global
loudspeaker instead of the actual traffic noise (road, railway
or aircraft). Fourth, the use and qualification of the
directional or omnidirectional sound source were
questioned. Fifth, the right positioning of the outside
loudspeaker will be analyzed.
This paper presents the first results of the experimental
measurement campaign on the qualification of the sound
sources for measuring the global façade sound insulation
On the influence of reference reverberation time on façade sound insulation measurements
No full textThe facade sound insulation measurements method is
standardized in ISO 16283-3, which is being revised.
The standard includes two measurement methods: the
element method and the global method. For the global
sound insulation of a façade, the standardized level
difference, D2m,nT is used. This level difference is
standardized to a reference value of the reverberation time,
T0, in the receiving room. For dwellings, T0 is equal to 0.5s.
This paper aims to evaluate the influence of the
reverberation time (T) correction of the receiving room,
with respect to the reference value T0, at the variation of the
T value, itself.
The results of measurements on site in receiving rooms with
different volume and different reverberation times are
compared
The DENORMS Round Robin test: Measurement procedure and post-processing of time data
Full text linkThe DENORMS Round Robin Test (RRT) is intended to study and improve the techniques used for the determination of the sound absorption coefficient of materials, with particular focus on the low-frequency range and on measurements in reverberation rooms. It is well known that the main reason why it is difficult to extend the frequency range of interest below 100 Hz is the low modal density. The modal behavior of a room is dependent on its geometry and this is one of the reasons why a discrepancy of the results coming from different laboratories can be found even if the same material is tested. This paper describes the measurement procedure developed to allow uniform acquisition and post-processing of acoustic response data of laboratories participating in the RRT, with and without absorbing materials inside. The tests and the post-processing operations performed on the measured data are also discussed in the paper
On the numerical modelling of reverberation rooms, including a comparison with experiments
Full text linkAt low frequencies the acoustic field in a reverberation room is not diffuse, and it should therefore be modeled by means of a deterministic approach. In this work, a finite element model was developed to include the modal behavior of the room. Dissipation in the empty reverberation room is taken into account by means of a volumetric approach, using an explicit closed-form expression for the complex speed of sound, on the basis of standard reverberation time measurements. Comparisons with measurements in a reverberation room show that the transfer functions and impulse response functions can be predicted fairly well.status: Accepte
Multilevel Functional Principal Component Analysis of Façade Sound Insulation Data
No full textThis work analyzes data from an experimental study on façade sound insulation, consisting of independent repeated measurements executed by different laboratories on the same residential building. Mathematically, data can be seen as functions describing an acoustic parameter varying with frequency. The aim of this study is twofold. On one hand, considering the laboratory as the grouping variable, it is important to assess the within-group and between-group variability in the measurements. On the other hand, in building acoustics, it is known that sound insulation is more variable at low frequencies (from 50 to 100Hz), compared with higher frequencies (up to 5000Hz), and therefore, a multilevel functional model is employed to decompose the functional variance both at the measurement level and at the group level. This decomposition also allows for the ranking of the laboratories on the basis of measurement variability and performance at low frequencies (relative high variability) and over the whole spectrum. The former ranking is obtained via the principal component scores and the latter via an original Bayesian extension of the functional depth
The denorms round robin test: Analysis of the preliminary results of the time data post-processing
No full textThe DENORMS Round Robin Test (RRT) on low-frequency sound absorption of materials has been completed, and data for all the involved European laboratories have been post-processed and analyzed. A large number of recordings from 12 very diverse reverberation rooms are available, either obtained with time reversal mirror or interrupted pink noise techniques. This paper presents an overview of the reverberation time values obtained in the different facilities and a study of empty-room results. The experimental data show a correlation between the measured reverberation time and the room features, embodied by the volume-to-absorbing surface ratio. The behavior of the rooms in different frequency ranges is also explored to identify possible information to be used in the interpretation of sound absorption measurements
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