Room Acoustics Prediction and Auralisation: Verification and Testing of New Methods in Room Acoustics Modelling.

室内声学模拟--模拟声波在封闭空间内的传播--是音频信号处理的基本应用之一。给定预定义的声源/听者位置和周围的几何形状，可以找到系统的结果房间脉冲响应(RIR)。与该RIR的卷积允许将任何音频信号放置在源位置的房间中，并由放置在接收器位置的收听者试听。这基本上允许在任何房间内听到任何声源。这项技术有三个主要应用：(1)音乐制作中的混响模拟：所有音乐都是在混响环境中创作的，无论是音乐厅还是为模拟最佳混响场而设计的算法。(2)建筑声学：在建筑/翻新之前对建筑物进行模拟和试听，以确定产生的音质并识别任何可能的变化。(3)虚拟环境建模：例如计算机游戏、虚拟现实应用和电影/电视后期制作，虽然约克和阿尔托的研究都包含了基于几何声学技术的标准房间声学模拟方法(其中声音被假设为一束光，但进行这种假设有相关的限制)，我们的大多数兴趣和努力都集中在直接求解声波方程的方法上，因此有可能全面、完整和准确地模拟封闭空间内的声场。最近的研究包括最优网格采样方案、频率相关的扩散边界、接收器的空间编码和源激励策略。方向性震源编码和实时可听化也被探索，结合了基于波的方法和几何方法的最佳方面，为进一步的研究和商业开发提供了巨大的和真实的潜力。因此，对于任何模拟的主要构成特征-源的激励和方向性、波的传播、边界相互作用和接收器编码-现在都存在解决方案。这与新的建模方法和使用图形处理单元来加快计算时间的可能性相结合。到目前为止，这项工作的大部分已经使用简单、易于测量的客观指标进行了验证，如房间模式分析、混响时间、极方向性图、边界特征等。因此，现在似乎适合处理更苛刻的模拟，以期验证此方法适用于更广泛的问题。我们将探讨一些方案，包括简单的、分析上微不足道的鞋盒形状的房间、以前发布的构成房间声学测量和模拟循环研究的基础的数据，以及基于其物理和声学直接测量的新的复杂空间的研究。此次访问的目的是促进一项基准研究，即在一些特定的理想和现实世界场景中使用和测试新的房间声学预测和可听化方法。因此，这将导致以下目标：(1)将代码整合到进行这项基准研究的适当框架中；(2)设计、执行和编写新房间声学预测和可听化方法的测试；(3)在第一个York-Aalto可听化工作坊组织并展示结果。该项目将导致我们的研究代码库的整合，以更容易地促进这项研究和未来的研究，至少发布一份主要期刊出版物，并在York和Aalto之间举办一次研讨会，以便对我们的结果进行初步传播和反馈，并进一步鼓励我们两个小组之间的持续合作。

Room acoustics simulation - modelling acoustic wave propagation within an enclosed space - is one of the fundamental applications of audio signal processing. Given pre-defined sound-source/listener locations and a surrounding geometry the resulting room impulse response (RIR) of the system can be found. Convolution with this RIR allows any audio signal to be placed in the room at the source location and auditioned by a listener placed at the receiver location. Essentially this allows any sound source to be heard within any room.There are three main applications for this technology:(1) Reverberation simulation in music production: all music is composed to be heard in a reverberant environment, whether a concert hall or an algorithm designed to simulate an optimal reverberant field.(2) Architectural Acoustics: where a building is simulated and auditioned before construction/renovation to determine the resulting acoustic quality and identify any changes that might be appropriate.(3) Virtual environment modelling: e.g. computer games, virtual reality applications and film/television postproduction, where various sound-sources are placed in and around a virtual environment with the potential for allowing interaction with the space.Although research at both York and Aalto encompasses standard room acoustics simulation methods based on geometric acoustic techniques (where sound is assumed to behave as a ray of light with the associated limitations involved with making such an assumption) most of our interests and efforts are focused on approaches that solve the acoustic wave equation directly, that therefore offer the potential for a full, complete and accurate simulation of the soundfield within an enclosed space. Recent research has included optimal grid-sampling schemes, frequency dependent diffusing boundaries, spatial encoding for receivers and source excitation strategies. Directional source encoding and real-time auralisation have also been explored, taking the best aspects of wave based and geometric approaches, and offering significant and real potential for both further research and commercial exploitation.Hence, solutions now exist for the main constituent features of any simulation - source excitation and directivity, wave propagation, boundary interaction, and receiver encoding. This is coupled with new modelling methods and the possibility of using Graphical Processing Units to speed up calculation times. Much of this work to date has been validated using simple, easy to measure objective metrics such as room mode analysis, reverberation time, polar directivity plots, boundary characteristics, etc. It therefore now seems appropriate to tackle more demanding simulations with a view to validating this approach for a broader range of problems. A number of options will be explored including simple, analytically trivial shoebox-shaped rooms, previously published data that formed the basis for a round robin study on room acoustics measurement and simulation, as well as the study of new, complex spaces based on their direct measurement, both physical and acoustic.The aim of this visit is to facilitate a benchmark study in the use and testing of new room acoustic prediction and auralisation methods for a number of specific ideal and real-world scenarios. This therefore leads to the following objectives: (1) Consolidation of code into an appropriate framework for carrying out this benchmark study; (2) design, carry out and write up testing of new room acoustic prediction and auralisation methods; (3) organise and present results at the first York-Aalto Auralisation Workshop.The project will result in a consolidation of our research codebase to more easily facilitate both this and future studies, at least one major journal publication and a workshop between York and Aalto to allow initial dissemination and feedback on our results, as well as further encourage the ongoing collaboration between our two groups.