Room acoustic synthesis can be used in Virtual Reality (VR), Augmented Reality (AR) and gaming applications to enhance listeners' sense of immersion, realism and externalisation. A common approach is to use Geometrical Acoustics (GA) models to compute impulse responses at interactive speed, and fast convolution methods to apply said responses in real time. Alternatively, delay-network-based models are capable of modeling certain aspects of room acoustics, but with a significantly lower computational cost. In order to bridge the gap between these classes of models, recent work introduced delay network designs that approximate Acoustic Radiance Transfer (ART), a GA model that simulates the transfer of acoustic energy between discrete surface patches in an environment. This paper presents two key extensions of such designs. The first extension involves a new physically-based and stability-preserving design of the feedback matrices, enabling more accurate control of scattering and, more in general, of late reverberation properties. The second extension allows an arbitrary number of early reflections to be modeled with high accuracy, meaning the network can be scaled at will between computational cost and early reverb precision. The proposed extensions are compared to the baseline ART-approximating delay network as well as two reference GA models. The evaluation is based on objective measures of perceptually-relevant features, including frequency-dependent reverberation times, echo density build-up, and early decay time. Results show how the proposed extensions result in a significant improvement over the baseline model, especially for the case of non-convex geometries or the case of unevenly distributed wall absorption, both scenarios of broad practical interest.

翻译：室内声学合成可用于虚拟现实（VR）、增强现实（AR）和游戏应用，以增强听者的沉浸感、真实感和外化感。常见方法是使用几何声学（GA）模型以交互速度计算脉冲响应，并通过快速卷积方法实时应用这些响应。另一种方法是基于延迟网络的模型，能够模拟室内声学的某些方面，但计算成本显著更低。为弥合这两类模型之间的差距，近期研究引入了近似声辐射传输（ART）的延迟网络设计，ART是一种模拟环境中离散曲面片之间声能传输的GA模型。本文提出了此类设计的两个关键扩展。第一个扩展涉及一种新的基于物理且保持稳定性的反馈矩阵设计，能够更精确地控制散射以及更一般地控制晚期混响特性。第二个扩展允许对任意数量的早期反射进行高精度建模，这意味着网络可以在计算成本和早期混响精度之间灵活扩展。将所提扩展与基线ART近似延迟网络以及两个参考GA模型进行了比较。评估基于感知相关特征的客观测量，包括频率依赖的混响时间、回声密度增长和早期衰减时间。结果表明，所提扩展相比基线模型有显著改进，尤其是在非凸几何或墙面吸声不均匀分布的情况下，这两种情况均具有广泛的实践意义。