Impact Thresholds of Parameters of Binaural Room Impulse Responses (BRIRs) on Perceptual Reverberation

Huan Mi,Gavin Kearney,Helena Daffern

doi:10.3390/app12062823

Abstract

This paper presents a study on the perceived importance of different acoustic parameters of Binaural Room Impulse Response (BRIR) rendering. A headphone-based listening test was conducted with twenty expert participants. Three BRIRs generated from simulations of three different rooms were convolved with a dry speech signal and used as reference audio samples. Four BRIR parameters, Initial Time Delay Gap (ITDG), Forward Early Reflections (FER), Reverse Early Reflections (RER) and Late Reverberation (LR) were systematically altered and convolved with a speech signal to generate the test conditions. A staircase method was used to obtain the threshold at which each BRIR parameter was perceived as different from the reference audio sample. The average perceived impact threshold of each parameter was then calculated across the twenty participants. Results show that RER removal and ITDG extension have a clear impact on the perceptual reverberation of speech audio. Subjects were less sensitive to FER removal. The effect of LR removal on perceptual reverberation is hard to distinguish. Therefore, RER and ITDG are of particular importance when designing artificial reverberation algorithms, whilst more research is needed to understand the perceptual contribution of LR. Minor changes in FER and LR are less significant.

Highlights

With the increasing popularity of Augmented Reality (AR) technologies, research into the plausible reproduction of virtual acoustic scenes that match the real world has gained importance [1]
Those data marked with the red colour are the maximum values that the parameters can be changed in this experiment, which means that the participant cannot distinguish any differences between the reference audio samples and the contrast audio samples when the corresponding parameters change, so the maximum values are regarded as the corresponding thresholds
Those data marked with the blue colour are the minimum values that the parameters can be changed in this experiment, which means that the participants can distinguish the nuances between the reference audio samples and the contrast audio samples when the corresponding parameters change

Summary

Introduction

With the increasing popularity of Augmented Reality (AR) technologies, research into the plausible reproduction of virtual acoustic scenes that match the real world has gained importance [1]. The rendering of the virtual audio should seemlessly match the real world acoustic for a convincing experience. The development of computationally efficient dynamic reverberation algorithms is essential to provide plausible virtual acoustic rendering on low-cost mobile devices. Reverberation is usually described by Room Impulse Responses (RIRs) in acoustics research. A RIR is the resultant pressure fluctuation measured at a receiving point due to an impulsive sound source at an arbitrary location in a room [3]. Room auralisation is achieved through convolution of source audio with a computationally derived or physically measured RIR [4]. Acoustic parameters that make up RIRs, including Early Reflections (ERs), Initial Time Delay Gap (ITDG) and Late Reverberation (LR), influence the resultant perceived reverberation

Methods

Results

Discussion

Conclusion