Managing Measurement Uncertainty in Building Acoustics

Abstract

In general, uncertainties should preferably be determined following the principles laid down in ISO/IEC Guide 98-3, the Guide to the expression of uncertainty in measurement (GUM:1995). According to current knowledge, it seems impossible to formulate these models for the different quantities in building acoustics. Therefore, the concepts of repeatability and reproducibility are necessary to determine the uncertainty of building acoustics measurements. This study shows the uncertainty of field measurements of a lightweight wall, a heavyweight floor, a façade with a single glazing window and a façade with double glazing window that were analyzed by a Round Robin Test (RRT), conducted in a full-scale experimental building at ITC-CNR (Construction Technologies Institute of the National Research Council of Italy). The single number quantities and their uncertainties were evaluated in both narrow and enlarged range and it was shown that including or excluding the low frequencies leads to very significant differences, except in the case of the sound insulation of façades with single glazing window. The results obtained in these RRTs were compared with other results from literature, which confirm the increase of the uncertainty of single number quantities due to the low frequencies extension. Having stated the measurement uncertainty for a single measurement, in building acoustics, it is also very important to deal with sampling for the purposes of classification of buildings or building units. Therefore, this study also shows an application of the sampling included in the Italian Standard on the acoustic classification of building units on a serial type building consisting of 47 building units. It was found that the greatest variability is observed in the façade and it depends on both the great variability of window's typologies and on workmanship. Finally, it is suggested how to manage the uncertainty in building acoustics, both for one single

Airborne sound insulation of a novel environmentally friendly straw wall

“…This value is perfectly comparable with the so far estimated value D 2m,nT,w = 64 dB. Indeed, on the one hand the measurement uncertainty of about 0.7-0.8 dB for the in-situ standard deviation [16,17] shall be taken into account, on the other hand the uncertainty of the evaluation method (± 2dB) shall be taken into account as well, leading to a perfect agreement between the estimated and the measured façade sound insulation.…”

Uncertainty of facade sound insulation by a Round Robin Test. Evaluations of low-frequency procedure and single numbers

“…In their paper, Scrosati and Scamoni [3] underlined that the standard ISO 12999-1 [4], on measurement uncertainties in building acoustics, gives the medium uncertainty on all the Inter Laboratory Tests (ILTs) and Round Robin Tests (RRTs) considered (and available at the time when the standard draft was being written), for airborne sound insulation, without distinction of the type of measurand. At the current level of knowledge and due to the number of cooperative tests available, this seems to be the only way to give an idea of the uncertainty magnitude.…”

“…In that paper Hopkins and Turner suggested the need for the low-frequency measurement procedure to improve the reliability of field measurements in rooms with non-diffuse fields (with volumes less than 50 m 3 ). This protocol was adopted in the revision of international standards on field measurements of airborne, impact and facade sound insulation for room volume below 25 m 3 . In his work on this topic Hopkins [20], presenting the main technical changes concerning the new ISO 16283 [21] series, described the low-frequency procedure for one-third octave bands below 100 Hz for rooms with volumes below 25 m 3 using additional corner measurements to determine the spatial average sound pressure level and using the 63 Hz octave band rather than one-third octave bands to measure the reverberation time.…”

Perceived Acoustic Quality and Effect on Occupants’ Satisfaction in Green and Conventional Residential Buildings

“…Even though measurements are perceived as the source of objectivity in the studies, variations in results are notorious. Scrosati and Scamoni [18] profoundly discussed problems with measurements and uncertainty in acoustics studies. The second approach (psychophysical) introduces the subjective opinion of the recipients of sound and cross-analyzes responses with on-site measurements, while the third approach focuses on the correlation between environment and people, targeting the cognitive process of sound appraisal [17].…”