La variabilità dei risultati nelle misure in opera di acustica edilizia

The evaluation of the variability of results in acoustic measurements in buildings is a matter of great interest among researchers, relating to the development of standards and legislation. This work focuses on the variability due to the mounting conditions and to the measurement method. The variability and issues related to the UNI 11367 standard were also analyzed. All the assessments were based on extended campaigns of acoustic measurements in buildings. In order to estimate the single contribution of the mounting conditions, a statistical approach taken from UNI ISO 5725-3 standard was studied and tested by measurements on the field. The opportunity to provide indications about “robust” technological solutions and to check afterwards the effect of mounting errors in a building are the main advantages of this method. The analysis continued with the collection of typical designs and workmanship errors and with the preparation of checklists for both the design and the realization phases. The aim was to provide appropriate support tools for designers and construction managers, in order to limit the effects of mounting conditions. The variability due to the measurement method was dealt with through the evaluation of the single variability factors considered more critical: the measurement technique and the position/type of source. The analysis was carried out by using both the statistical approach defined above and empirical experiments. Here an alternative manual scanning technique was described and tested on the field. Finally, the variability linked to the UNI 11367 standard (regarding the sound classification of single properties) was assessed. Through many measurements carried out on non-serial buildings, the most critical aspects related to the sampling procedure (usually used for serial buildings) and to the draft guidelines U20002150 (referring to the application of the acoustic classification for nonserial buildings) was shown.