UTILISATION DE L'INDICE RASTI ET DU TEMPS DE RÉVERBÉRATION INITIAL POUR L'ANALYSE DES PROBLÈMES D'ACOUSTIQUE ARCHITECTURALE

Abstract
Correlation between the Rasti index and the impulse response, namely the EDT-5, EDT-10 and EDT-15 dB, has been analysed, both in laboratory and during experiments conducted in multi-purpose halls and in large amphitheatres equipped with sound reinforcement systems. The close relationship between the RASTI index and the EDT measurements will be demonstrated. We will also show the necessity to measure the EDT's at the same localization and with the same directivity as the normal sources of the hall ; for exemple, with the use of a powerful omnidirectional source in order to study the acoustical behavior of orchestra shell (Louis Fréchette Hall of the Grand théâtre de Quebec or Albert Rousseau Hall) or with the measurement of impulse response through the sound system of a large amphitheatre (Montreal Olympic Stadium). In addition to provide a better understanding of the parameters governing the intelligibility, the proposed approach could be very helpful to the acoustical design of new and to be renovated halls (New Richmond Theatre, The National Theater Institute of Montreal).