Qualification of balance in opera houses: Comparing different sound sources

The balance between singer and orchestra in opera houses has been receiving increasing interest in the recent years. This characteristics is in fact at the core of the functionality of opera houses and its tuning deserves great attention both in the qualification and in the design process. Unfortunately, a standardized method for the measurement of balance is still not available in the technical norms. In this work a set of data is measured in the Municipal Theatre of Modena and the use of omnidirectional and different directional sound sources to study the balance is investigated. In particular an antropometric sound source and two directional loudspeakers are compared and also two different omnidirectional sound sources are employed. Several combinations are obtained and the merits and the limits of the different measurement chains are presented and discussed. It is seen that a severe scatter of data may occur depending on the measurement chain. The results are also discussed in relation with former computer simulations in other theatres in order to fix the best available measurement chain for the qualification of balance.