A review of sound strength criterion in acoustical design of concert halls

An important objective parameter in the acoustical design of concert halls is the sound strength G(dB).This parameterG is denoted as the sound level in an auditorium normalized to the sound power level of the source.Besides the total level of G in the auditorium,the early(80 ms) and late sound field,G_E and G_L should also be considered separately because the causing factors and subjective effects of these fields are so different.A surprising result from a series subjective experiments showed that the bass perception in a concert hall is highly related to the strength factor at lowest frequencies,not the reverberation time factor as formerly considered.It was commonly recognized before that the most important component of listener envelopment(LFV) is the late energy arriving at a person's ears from lateral directions only.Now we know the strength factor G should be included,and the total late energy G_late is a better component of LFV than late lateral energy.Some LFV predicted formula has been devised accordingly for acoustical design purpose.Criterion for acceptable loudness is reviewed in this paper.An important new discovery on this subject shows that listeners' judgment of loudness in a hall is based on the strength of the reverberant field or on the vision of the distance of the source—-probably on both.Some uncertainties remain regarding objective correlates of 'intimacy'. The mean forte sound pressure level of tutti-sound,a so called new criterion parameter was recommended by Wu to describe the subjective loudness perception in concert halls during the performance.The author gives criticism on this recommendation and also points out neither the measurement procedure nor evaluation method is feasible.