Improvement of the Acoustics under the Balcony in Auditoria Using the Electro-Acoustic Method—A Study with a Full-Scale Model

In auditoria, the acoustical properties of audience areas located under balconies are regarded as inferior to the main area. This is caused by the reduction of direct and reflected sound energy due to the smaller open area and the reduction of diffusive energy due to the limited acoustical space. In this paper, a new electro-acoustic system is proposed to compensate for this acoustical condition. The proposed system is a non-regenerative system and consists of directional microphones, head amps, a convolver, a matrix processor, amplifiers, and ceiling loudspeakers located under the balcony. The loudspeakers, located at positions corresponding to measurement points across the balcony, recreate the reflecting sound from above the balcony area, which otherwise fail to reach to the listeners under the balcony. The authors have examined the proposed system's performance via two methods: acoustical measurement using a full-scale model and a corresponding psycho-acoustical experiment. The results showed that the energy of the reflections from above the system was the same or more than that without the balcony, and the decay curve with the system was almost the same as that without the balcony. The MUSHRA method was used in the psycho-acoustical experiment, which focused on the evaluation of apparent source width (ASW) and listener envelopment (LEV). The results of the experiment show that the system is significantly better for all tests to the use of no system and that the system is superior to a standerd PA (delay system).