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The known criteria of room acoustics are not sufficient to characterize the quality of concert halls. To obtain more specific information on the acoustic qualities of concert halls, the author went on tour with the Cleveland Orchestra, making measurements in 15 concert halls. These measurements revealed that the dynamic range of performed music and also the tempo are different in the several halls. The dynamic range depends on the noise level of the room and the state of sound diffusion. The tempo of music is at a maximum in concert halls which have optimum reverberation time and diffusion.

In recent years one has found essential criteria of room acoustics which are responsible for good intelligibility of speech addresses in auditoria. Concert halls which have been built according to these principles are not fully satisfying as to the performance of classical music. The high intelligibility which one deduces from the first reflection pulse and the envelope of the decay curve is not of primary importance for classical music which demands, above all, fullness of tone and blend. An opportunity was afforded to go on tour with the Cleveland Orchestra and to make statistical measurements in 15 different auditoria during their concerts. It has been resulted that the dynamic range attainable by the orchestra is directly dependent on room acoustic qualities. The lower limit of loudness is given by the noise level, variable in the different halls, and the upper limit by diffusion and absorption which are also responsible for the quality or timbre. The behavior of the orchestra is revealed further from the tempo of the music, with the tendency that in the better concert hall with the optimum reverberation time little absorption and good diffusion allow a faster tempo.

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