Bemerkungen zur geometrischen Raumakustik

The paper deals with the first sound reflections following the direct beam from source to listener. The number of these reflections can be greatly increased by sound mirrors suitably tilted and placed at the upper parts of the side walls in the neighbourhood of the sound source. If these first reflections occur in the 50 ms interval after the arrival of the direct sound a reinforcement takes place. Some formulae are given relating this effect to the energy density in the diffuse sound field.

The second part of the paper describes some practical applications to rooms, in which sound mirrors improve the hearing conditions and especially the intelligibility of speech. They are: tho rebuilt opera house at Hamburg, the big hall in the students hostel at Bonn, and the theatre at Hannover.