Under-balcony acoustics in concert halls: Single source versus an array of multiple sources

The conventional measurement protocol using a single omnidirectional sound source may have limits or uncertainty in objective acoustical analysis of a performance hall. This study conducted monaural and binaural impulse response measurements with an array of 16 directional loudspeakers for quantitative acoustical assessment of specifically under-balcony area in a concert hall. The measurements were executed in a real performance hall. The measured time- and frequency-domain responses as well as the results of room acoustical parameters including binaural parameters were compared to the ones measured with a single omnidirectional source. The results were also compared to the ones taken at the main orchestra seating area. The time-domain responses showed a clear distinction particularly in early responses between single source and multiple sources. On the other hand, the magnitude of frequency response showed significantly lower at frequencies above 1 kHz than the one measured at the main area. The results of a binaural parameter, IACC, were found to be marginal between single source and multiple sources but critically different between under-balcony area and main area. Variations were also observed in the results of other room acoustical parameters when compared either between single source and multiple sources or between under-balcony area and main area.