Conference_programme: 18.8 - Recent trends in numerical modeling: protocols and reliability

Lecture: Predictions of room and intelligibility criteria in lecture halls

Author(s): Fratoni Giulia, D'Orazio Dario, Garai Massimo

Summary:
This paper compares measured, calculated and simulated intelligibility criteria in some university lecture halls. They are charaterised by large volumes (greater than 500 m3) and a highly variable number of students over time, a situation strongly different from high school classrooms that have a smaller size and a constant occupancy. This study takes into account reverberation time (T), sound propagation of speech levels (SP), early-to-late sound ratios (C50) and speech transmission index (STI). These acoustic parameters were evaluated by performing acoustic measurements according to technical standards ISO 3382 and IEC 60268-16. In addition, analytical predictions have been done according to previous literature concerning sound energy distribution (Barron and Lee’s theory, Hodgson’s model, Astolfi, Corrado and Griginis’ findings) and the recent Italian technical standard UNI 11532. Moreover, these lecture halls represent a typology particularly suitable for the geometric approximation required in the numerical modelling process. In fact, some architectural features, such as shape regularity and volume size, can improve the reliability of Geometric Acoustic (GA) simulations. Thus, measurements results are compared both with values obtained analytically and with values obtained using a GA software. Preliminary conclusions on the comparison between measurements, analytical predictions and simulated criteria are discussed.

Corresponding author

Name: Ms Giulia Fratoni

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Country: Italy