Experiments on a multiple loudspeaker 3D audio system for reproduction of sound fields captured with a spherical microphone array

Realistic auralizations of sound fields have an enormous potential for many engineering, entertainment, and architecture applications. The research and development on immersive and 3D audio has been providing new solutions both for the capture and for the reproduction of sound fields and acoustical environments. This paper presents a study to assess the capacity of a recording and reproduction system to preserve the spatial properties of real 3D sound fields. The system is based on the audio capture through a 64-microphone spherical array and reproduction through a spherical layout of loudspeakers installed inside an anechoic chamber, making use of ambisonics format. A methodology to perform an objective analysis was proposed, using the spherical array of microphones as the listener of the implemented reproduction system, recording sound fields generated by the system itself or by external loudspeakers, and comparing audio signals before and after the processing by the system. Subjective listening tests were also performed by a set of individuals, evaluating the immersive experience provided by the system reproducing sound fields captured with the array in different environments: a car cabin, an aero generators farm, a tennis court, and a concert hall. Objective tests attested the system capacity to reproduce the location of the sound source adequately, although without a uniform source location separation along the different positions. The subjective listening tests revealed that the system provides different levels of accuracy on the perceived positions of the sound sources depending on their original positions and on the sound type. The perception of the overall original acoustic environments is achieved successfully, allowing the listeners to feel transported to the all the original places where the 3D audio capture took place.