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：室内声学合成技术可应用于虚拟现实（VR）、增强现实（AR）及游戏领域，以增强听者的沉浸感、真实感与声像外化感知。常用方法包括采用几何声学模型实时计算脉冲响应，并利用快速卷积方法实时施加这些响应。另一种基于延迟网络的模型能以显著较低的计算成本模拟室内声学的特定方面。为弥合这两类模型间的差距，近期研究提出了近似声学辐射传递的延迟网络设计——该几何声学模型模拟声能在环境离散表面单元间的传递过程。本文提出此类设计的两项关键扩展：首先，引入基于物理且保持稳定性的反馈矩阵新设计，实现对散射及更广义的后期混响特性更精确的控制；其次，支持以高精度模拟任意数量的早期反射，使得网络能在计算成本与早期混响精度之间按需扩展。通过客观测量感知相关特征（包括频率相关混响时间、回声密度累积及早期衰减时间），将所提扩展与基准ART近似延迟网络及两种参考几何声学模型进行对比。结果表明，所提扩展相比基准模型实现显著改进，尤其适用于非凸几何结构或墙面吸声分布不均的场景——这两类场景均具有广泛的实际应用价值。