# Auralization of High-Order Directional Sources from First-Order RIR Measurements
## 3 Listening Experiment--Comparative Study
### Design and Implementation
Depending on the tested multistimulus set, those colored squares correspond either to all auralization techniques for a fixed beam direction or to all beam directions for a fixed auralization technique. Figure 5: Position of source, listener, and reflectors (R1,..,R4) in György Ligeti Saal, Graz. An ideal 3 rd-order max-\(r_{\text{E}}\) weighted beampattern with a dynamic range of 30 dB is shown in gray. For the listening experiment we used the beam directions \(\varphi_{S}=[0^{\circ},180^{\circ},90^{\circ},45^{\circ},-36^{\circ},-82^{ \circ}]\). As VR game engine we used Unity ([[https://unity.com/](https://unity.com/)]([https://unity.com/](https://unity.com/))) and the experimental game was played using the HTC VIVE, i.e., system comprising head-mounted display (HMD), controllers, and tracking. The tracking data, i.e., head rotations, from the HMD was sent to Reaper ([[https://www.reaper.fm](https://www.reaper.fm)]([https://www.reaper.fm](https://www.reaper.fm))) via OSC [49], where the audio processing was implemented. While [PERSON] and [PERSON] [50] stated that short onsets and transient signals overall simplify localization, [PERSON] et al. [7] discovered that such signals are localized significantly closer to the IKO. In order to create a large scenery of perceivable auditory objects distributing to various remote locations with regard to the IKO, [PERSON] et al. [7] recommends using signals with slow onset. For conditions with clear effects, we therefore used a 1.5 s long pink noise burst with fade-in and fade-out times of 500 ms (linear fades) and 500 ms silence at the end. For encoding and multi-channel convolution with IKO control filters, directivities, and RIRs we used the mcfx ([[http://www.matthiaskronlachner.com/?p=1910](http://www.matthiaskronlachner.com/?p=1910)]([http://www.matthiaskronlachner.com/?p=1910](http://www.matthiaskronlachner.com/?p=1910))) plug-ins and as binaural renderer of the Ambisonic signals we used the BinauralDecoder ([[https://plugins.iem.at/](https://plugins.iem.at/)]([https://plugins.iem.at/](https://plugins.iem.at/))) [18; 41]. The ear signals were played back via headphones (AKG 702) plugged into an external audio interface (RME MadiFace & RME FireFace UCX). Note that an orientation mismatch \(<5^{\circ}\) between different arrays used for measuring the RIRs (cf. the IKO vs. Cubelet, and ST450 vs. em32) can almost not be avoided. Thus, the authors perceptually aligned the auralization techniques for \(\varphi_{S}=180^{\circ}\). During informal listening experiments (by four participants) we found that all auralization techniques under test obey a high overall sound quality (no artifacts or temporal smearing). However, the overall timbre slightly varies across the techniques as we employed technique specific measurement hardware (e.g., Cubelet vs. IKO). While a global and steering-direction-independent equalization was not feasible, the techniques were perceptually equalized using a parametric multi-band EQ for a fixed steering direction \(\varphi_{S}=180^{\circ}\) (pointing to the listener). _Input Method:_ During the experiment, participants were asked to indicate the position (i.e., direction and distance relative from the listener) of the perceived sound and to follow a certain procedure: (i) point to a colored square to select a stimulus for looped playback, (ii) pick-up the correspondingly colored ball by pointing towards it and pressing the trigger, (iii) with trigger pressed, point to the perceived direction and adjust the distance by moving the thumb on the controller track pad, (iv) release the trigger to drop off the ball at the intended position, (v) proceed until all balls are positioned, then save responses and proceed to next multistimulus set. Participants were allowed to reposition any ball as often as desired until the responses of the entire multistimulus set were logged in. Figure 6: Screen shot of VR-rendered environment.