# Auralization of High-Order Directional Sources from First-Order RIR Measurements
## 4 Conclusions  
In this contribution we presented the concept and a comparative perceptual evaluation of a source-and-receiver-directional ARIR capture and processing approach (SRD ARIR) with a variety of technical alternatives. Although the proposed SRD ARIR rendering method only employs a small set of first-order directivities (omnidirectional and figures of eight aligned with \(x\), \(y\), and \(z\)) in the measurement, the approach produced auralization of higher-order directional source and receiver configurations that was performing well in the comparison. Its directional resolution enhancement involves the Ambisonic spatial decomposition method (ASDM) that we could extend to both sides of the measured ARIRs.  
In the dynamic headphone-rendering-based evaluation, we employed the highly directional icosahedral loudspeaker (IKO) as a virtual source because of its well-described measured directivity and the well-studied perceptual effects it causes. For the sake of reproducibility and to obey optimal externalization the auralization listening experiment was done within a head-mounted-display visualization of the virtual environment. Interactive visual objects were used to indicate auditory event locations in space.  
The proposed SRD ARIR method performed similarly accurate as the reference auralization based on multiple-orientation binaural room impulse responses (MOBRIRs). We found no significant difference for the perceptual attributes of localizability, direction, and distance. Although most of the alternative techniques performed comparable to the reference auralization, the SRD ARIR technique has benefits in terms of modularity and efficiency: It only requires a small number of hardware channels, and SRD ARIRs offer a generic interface between RIRs and source and receiver directivities. Any application requiring a flexible exchange of directivities can potentially benefit from the small number of responses needed to characterize the room (be it measured or simulated).  
\begin{table}
\begin{tabular}{c c c c} \hline \hline \(Em\) & \(As\) & \(Sr\) & \(Si\) \\ \hline
0.55 m & 0.28 m & 0.28 m & 0.51 m \\ \hline \hline \end{tabular}
\end{table}
Table 4: Mean absolute distance offset to \(Dy\) per auralization technique over all tested beam directions \(\varphi_{S}\).  
A collection of room responses measured for the study, responses of the listening experiment, the statistical analysis, and high-resolution directivities of the arrays is made available online ([[https://phaidra.kug.ac.at/o:104417](https://phaidra.kug.ac.at/o:104417)]([https://phaidra.kug.ac.at/o:104417](https://phaidra.kug.ac.at/o:104417))).  
Conceptualization, M.Z. and F.Z. ([PERSON]); Writing--Original Draft Preparation M.Z. and F.Z. ([PERSON]) with periodic contributions by [PERSON] ([PERSON]); Writing--Review & Editing, M.Z. with contributions of [PERSON]. ([PERSON]), and [PERSON] ([PERSON]); Software, M.Z. with periodic contributions by [PERSON] ([PERSON]) and [PERSON] ([PERSON]). listening Experiment Implementation, M.Z.; Listening Experiment Design, M.Z., [PERSON] ([PERSON]), and [PERSON] ([PERSON]); Listening Experiment Conduction: F.Z. ([PERSON]) with periodic contributions by [PERSON]; Data Analysis, F.Z. ([PERSON]) with periodic contributions by [PERSON] ([PERSON]) and M.Z.; Measurements, M.Z., [PERSON] ([PERSON]), and [PERSON] ([PERSON]). All authors have read and agreed to the published version of the manuscript.  
The major part of the work was carried out within the OSIL project AR 328-G21 that was funded by the Open Access Funding by the Austrian Science Fund (FWF).  
We thank [PERSON] for his companionship in pursuing the proposed technique over the past years, and all voluntary listeners for their participation in our listening experiments.  
The authors declare no conflicts of interest.