Terence Caulkins

Radiation control applied to sound synthesis: An attempt for ‘‘spatial additive synthesis.’’

Sound synthesis is generally focused on the reproduction of the spectral characteristics of the source or on the simulation of its physical behavior. Less attention is paid to the sound playback step which generally results in a simple diffusion on a conventional loudspeaker setup. Stating the perceptual importance of a faithful reproduction of the source radiation properties, the paper presents a method combining a synthesis engine, based on physical modeling, with a rendering system allowing an accurate control on the produced sound‐field. Two sound‐field synthesis models are considered. In the first one, a local 3D array of transducers is controlled by signal processing for creating elementary directivity patterns that can be further combined in order to shape a more complex radiation. The dual approach consists in surrounding the audience with transducer arrays driven by wave field synthesis in order to simulate the sound field associated to these elementary directivity patterns. In both cases, the di...

New implementation of multi-microphone recording technique to simulate music ensembles in room acoustic auralizations

This paper describes a method to record large musical ensembles for use in computer simulations and auralization. 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 sectors by convolution with the models outputs. The method permits recording and simulating an entire orchestra with its directivity, including the movement of the musicians while playing. The approach is geared towards achieving a high quality of orchestral musicianship and sense of orchestral ensemble while maintaining high spatial accuracy and quality of timbre while also minimizing recording artifacts such as proximity effect. The method has been implemented with renowned performers and orchestras, and has been used in the auralization of several new concert hall design projects.

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.

Comparison of headphone- and loudspeaker-based concert hall auralizations

In this research, a spherical microphone array and a dummy head were used to measure room impulse responses in a wide variety of concert and recital halls throughout New York State. Auralizations were created for both headphone playback and second-order ambisonic playback via a loudspeaker array. These two systems were first evaluated objectively to determine the level of accuracy with which they could reproduce the measured soundfields, particularly with respect to important binaural cues. Subjects were then recruited for listening tests conducted with both reproduction methods and asked to evaluate the different spaces based on specific parameters and overall subjective preference, and the results of the two playback methods were compared.

Using a spherical microphone array to analyze stage acoustics.

A spherical microphone array, capable of beamforming, has been constructed to measure sound fields using second‐order ambisonics. The design of the microphone is based on the work by Duraiswami et al. using equations for scattering off a rigid sphere. The 16‐channel array was used to measure nine different concert‐hall stages around the state of New York, with multiple positions recorded to analyze their acoustical behavior. Additional measurements with an omnidirectional microphone were obtained to determine A.C. Gade’s stage support parameter for comparison purposes. Based on the measurements, alternative methods will be discussed to obtain better descriptors to quantify stage acoustics based on the additional spatial information the spherical microphone provides. Additionally, the work by Dammerud in developing geometric parameters based on comparisons between omnidirectional measurements and architectural dimensions will be utilized. A comparison between parameters by Dammerud and information extracte...

Using a spherical microphone array to analyze concert stage acoustics

A 16 channel spherical microphone array has been designed and constructed to measure high order Ambisonic sound fields, based on equations for scattering off of a rigid sphere. This microphone has been used to capture and characterize the acoustics of nine different concert hall stages around the state of New York. Musicians have been invited to perform in real-time in auralizations of each hall and participate in a subjective preference test based on their experience. The preference tests have been analyzed using multi-dimensional scaling methods and compared with acoustical data derived from a beamforming analysis of each stage. Additional comparisons with A.C. Gades omnidirectional parameters (stage support, early ensemble level) and geometric parameters described by J. Dammerud are performed.