Development of Room Acoustic Prediction and Evaluation Tools for Designers

Abstract

We develop room acoustic prediction and evaluation tools for designers to be used in halls and conference areas where the design of acoustical performance is essential. The designers, with no specialized knowledge of acoustics, are able to examine the tools at an early stage of the project. The interface tool consists of the 3D CAD software-Rhinoceros, and its plug-in tool-Grasshopper. The designers first build a room model on Rhinoceros and locate the sound source and the receiver points in the model. They then set the calculation conditions via Grasshopper, such as room use and type of interior finishes. Next, room sound propagation is calculated using the ray tracing method in the external python programs. Then, acoustic indices, such as the average sound absorption coefficient and clarity, are predicted. These indices are automatically evaluated according to the room use, and the evaluated results are visualized in the room model on Rhinoceros. This paper outlines these tools and exhibits the agreement of predicted and measured indices in a small hall. These tools are applied to a lecture room with complicated ceiling ribs, and an office with a stairwell, which are difficult to examine by the conventional reverberation formula.