Speech level as a parameter for evaluating classroom acoustics

In this paper we present measured acoustic parameters of BMSTU classrooms of average capacity, designed for holding lectures and seminars. To characterize the classroom acoustics following parameters are selected: the reverberation time, the speech transmission index STI, and the sound level of speech of the lecturer, which is called the speech level in this work. A parameter for characterizing the spatial speech level distribution has been proposed and investigated. The parameter is non-local, therefore the evaluation of acoustic quality by this parameter turns out to be differentiated in long classrooms. A simple method of measurement of speech level in real conditions at different distance from the source is proposed. The relationship of this parameter with other acoustic parameters of classrooms, sizes and internal finishing is analyzed.