Optimum Reverberation for an Auditorium

The time of reverberation of a room depends upon the number of people present. The optimum time has been determined experimentally for a number of halls by having the audience gradually increase while musicians play as constantly as possible, the judgment of trained musicians being obtained as to when the best acoustics were secured. The optimum reverberation (for a sound ${10}^6$ × threshold intensity) was found to be the same for speech and for singing as for instrumental music within.05 sec., the mean being 1.03 sec. for a room of less than ${350\mathrm{m}}^3$. For larger rooms the optimum $T$ is given by the equation $(10.23-{log}_{10}V)T+0.97(0.4-{log}_{10}V)T^{\frac{1}{2}}=6\mathrm{}$. The acoustics of various concert halls and of the Big Theater in Moscow are in agreement with the formula, which has previously been published.