###### 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.  
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measured RIRs. Such reverberators should be dynamic, in that the acoustic parameters should change with the six degrees of freedom movement of the listener. They should also be rendered using binaural audio techniques for effective spatialisation. The reverberation proposed in this paper therefore refers to binaural reverberation and the corresponding RIRs are Binaural Room Impulse Responses (BRIRs); however, rendering with real-world BRIRs for AR experiences requires prior knowledge of the location that the AR experience will be consumed. Computational derivation of an unknown room's acoustic for an AR experience, for example through visual depth mapping [5] or on the fly acoustic excitation [6] is challenging and requires a computationally based real-time reverberation model, even if some room acoustics data are physically extracted through measurement.  
Alternatives to direct convolution of source material with BRIRs include the use of reverberators entirely based on geometric or wave-based acoustic models or feedback delay networks (FDNs) [7]. Hybrid models that, for example, utilise both FDN reverberation alongside components of the RIR (such as the late reverberation) can also be conceived.  
In reality, AR enabled systems should use portable, low-power mobile computing devices and reverberation algorithms with low computational complexity [3]; however, in an effort to simplify artificial reverberation algorithms, it is necessary to understand the influence of the acoustic parameters on the overall perceived reverberation and the thresholds of perception for each of these parameters. Parameters with the most perceptual relevance could therefore be emphasised in the reverberator design and other parameters given less importance.  
It is therefore the purpose of this paper to explore the impact thresholds of parameters of BRIRs on perceptual reverberation, providing the foundational research for new artificial reverberation algorithms.