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

Abstract

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).

Under-Balcony Acoustics Improvement with Simple Electro-Acoustic Means: A Theoretical Development and Numerical Simulations

“…(2) which leads to: (3) where the coupled dumping constants are: (4) and where the coefficients e 11 , e 12 , e 21 and e 22 are given from the initial conditions. In the case of impulse responses, the source signal is an infinitely short impulse of duration Dt.…”

“…In their paper, they described the conceptual design of this system and gave some advices about its installation. Watanabe and Ikea 3 presented measurements made on a simple model of coupled rooms equipped with an electro-acoustic system used to increase the coupling. These measurements showed that such a system could indeed reduce the effect of the balcony overhang, but this system was an "inline" reverberation enhancement system which has a more complex design than a regenerative one.…”