MEASUREMENTS AND SIMULATIONS OF SPEECH TRANSMISSION INDEX (STI), DEFINITION (D50) AND REVERBERATION TIME (TR) IN CLASSROOMS

Abstract

Using an impulsive technique, the speech transmission index (STI), reverberation time (TR), and D50 were measured, which are the most relevant acoustic descriptors for classroom evaluation, where verbal exposure is the mean of communication between teachers and students. The evaluation took place in two buildings of the Federal University of Paraná (UFPR), one built in 1960s and the other in 2016. Besides providing the real acoustic condition of the rooms, the STI values were also used as an adjustment parameter for computational simulations with ODEON software. In a second fase, new simulations were made in order to determine which and what kind of improvement can requalify the classrooms at UFPR so that there is no demerit in the learning due to the physical structure where the lessons take place. The measured values of STI, TR and D50 show that in the oldest building, except for a single room that still preserves the original acoustic ceiling, has reasonable values, meaning that it is not ideal for lessons. It was possible to verify that the rooms which over time had their acoustic ceiling changed by PVC, presented a decrease in acoustic quality. The newest building built in 2016 has rooms with good acoustic conditions for teaching and learning.