Spatial Interpolation of Room Impulse Responses Using Information on Early Reflection Directions

Abstract

In recent years, with the widespread advent of 3D movies and VR (virtual reality), studies have been advanced. In particular, opera and orchestral concerts are preferred in spaces with unique reverberations, e.g., concert halls. However, we cannot enjoy the recorded concerts in a homely. To obtain resonance, the room impulse response is measured; however, the impulse response is a measurement value at a certain point, and the measurement process is time-consuming and costly. Therefore, an interpolation method has been proposed to reduce the number of impulse response measurement points. Interpolation is a method of estimating the impulse response of the position between the microphones from acoustic models and actual measurement data, and performing numerical calculations. A problem with the conventional method is that the accuracy of the plane wave of the impulse response, i.e., early reflections portion is low. In this study, we further perform the direct wave/plane wave splitting method related to the conventional impulse response, splitting the plane wave into two parts, the early reflected wave and reverberation. We propose a method to determine a suitable model and range for early reflections that, which may help improve accuracy. In the first experiment, we determine the cutout position to split the plane wave; in the second experiment, we propose a method to compare the accuracies of early reflected and synthesized plane waves with the conventional results. Based on the results of the aforementioned methods, we confirm the effectiveness of the proposed method.