Semi-anechoic music recording using multi-microphone technique to simulate orchestra directivity in room acoustic auralizations

Over the last two decades, computer generated auralizations have become increasingly relevant to the design process of new performance spaces. Auralizations are based on anechoic material, and simulation realism is often limited by a small repertoire of recordings and the challenges of simulating an orchestra’s complex sound radiation characteristics. To address some of these issues, this paper describes a method to record—in semi-anechoic conditions—large musical ensembles for use in computer simulations. The method uses a multi-microphone hemispherical array distributed over an orchestra playing on a hard floor. A ray-tracing program models the orchestra as sectors of a hemisphere corresponding to each microphone location. Microphone signals are then mapped to their respective source sector. The method permits to record and simulate an entire orchestra with its directivity, including the movement of the musicians while playing. The paper describes the influence of the radius and angular resolution of the microphone array; it also investigates different source configurations in the computer model. The method has been implemented with renowned performers and orchestras and has been used for auralizations of several new concert hall design projects.