Stereo reverberation

Investigating the reasons why reproduced music gives an impression different from that which a listener receives during a concert, it was found that the distribution of the sound over the room is essential. Although stereophonic reproduction can give a sufficiently accurate imitation of an orchestra, it is necessary to imitate also the wall reflections of the concert hall, in order that the reproduction may be musically satisfactory. This can be done by means of several loudspeakers, distributed over the listening room, to which the signal is fed with different time-lags. The diffused character of the artificial reverberation thus obtained seems to be even more important than the reverberation time. Likewise, when a live orchestra is playing in an acoustically unsatisfactory hall (e.g., a theater), the diffuseness of the sound field and the reverberation time may both be improved by picking up the music by means of a directional microphone and repeating it through loudspeakers with different retardations. The audience does not experience the improvement consciously and ascribe it to the orchestra playing better. The performers, however, are aware of the change in the acoustics as making the hall more playable.