Abstract
Estimating and parameterizing the early and late reflections of an enclosed space is an interesting topic in acoustics. With a suitable set of parameters, the current concept of a spatial audio object (SAO), which is typically limited to either direct (dry) sound or diffuse field components, could be extended to afford an editable spatial description of the room acoustics. In this paper we present an analysis/synthesis method for parameterizing a set of measured room impulse responses (RIRs). RIRs were recorded in a medium-sized auditorium, using a uniform circular array of microphones representing the perspective of a listener in the front row. During the analysis process, these RIRs were decomposed, in time, into three parts: the direct sound, the early reflections, and the late reflections. From the direct sound and early reflections, parameters were extracted for the length, amplitude, and direction of arrival (DOA) of the propagation paths by exploiting the dynamic programming projected phase-slope algorithm (DYPSA) and classical delay-and-sum beamformer (DSB). Their spectral envelope was calculated using linear predictive coding (LPC). Late reflections were modeled by frequency-dependent decays excited by band-limited Gaussian noise. The combination of these parameters for a given source position and the direct source signal represents the reverberant or “wet” spatial audio object. RIRs synthesized for a specified rendering and reproduction arrangement were convolved with dry sources to form reverberant components of the sound scene. The resulting signals demonstrated potential for these techniques, e.g., in SAO reproduction over a 22.2 surround sound system.