# Head-Related Transfer Functions for Dynamic Listeners in Virtual Reality
## 3 Subjective Experiments Overview  
There were two sessions of subjective experiments: static localization (Section 4) and dynamic 6-DoF virtual reality (Section 5). The experiments were conducted starting with the dynamic VR experiment followed by the static localization experiment, but reported here in reversed order for readability. There was a gap of more than 12 months between the respective experiments. The dynamic VR experiment was further divided into a main experiment and a follow-up, where two additional scenes focusing on localization in elevation were evaluated a month after the main experiment. The following paragraph provides an overview of the participants in each of the subjective sessions.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Template** & **Target** & **Unsigned Elevation Error** & **Quadrant Errors** \\ \hline Modeled & Modeled & 31.0\({}^{\circ}\) (CI 29.8\({}^{\circ}\) to 32.2\({}^{\circ}\)) & 16.0\% (CI 13.5\% to 18.6\%) \\ Measured & Measured & 37.5\({}^{\circ}\) (CI 34.9\({}^{\circ}\) to 40.3\({}^{\circ}\)) & 20.3\% (CI 15.9\% to 25.1\%) \\ Measured & Modeled & 50.3\({}^{\circ}\) (CI 49.0\({}^{\circ}\) to 51.7\({}^{\circ}\)) & 41.7\% (CI 38.4\% to 45.7\%) \\ Modeled & Generic & 48.7\({}^{\circ}\) (CI 46.8\({}^{\circ}\) to 50.7\({}^{\circ}\)) & 41.9\% (CI 38.7\% to 44.8\%) \\ Measured & Generic & 46.6\({}^{\circ}\) (CI 45.0\({}^{\circ}\) to 48.2\({}^{\circ}\)) & 39.6\% (CI 37.3\% to 41.9\%) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Auditory-model-based predicted mean unsigned elevation errors and quadrant errors with the bootstrapped 95% confidence intervals.  
Figure 2: Auditory-model-based predictions of the (**a**) local (\(\theta\leq 90^{\circ}\)) elevation RMS error and (**b**) quadrant errors (\(\theta>90^{\circ}\)). The error bars denote the bootstrapped 95% confidence intervals of the mean. The applied model is the [PERSON] et al. (2019).  
The sample size for the subjective experiments was 12 participants, limited only due to the difficulties in ascertaining high fidelity measured and modeled individual HRTF sets. Subgroups of the subject pool with slight variations in numbers participated in the two experiment due to availability. For the _static localization experiment_, 8 people took part (1 female). Their average age is 37.4 years (SD = 11.7). In total, 12 people (2 female) took part in the _main dynamic 6-Do VR experiment_. Their average age is 38.6 years (SD = 9.8). In the _follow-up dynamic 6-DoF VR experiment_, the two scenes focusing on localization in elevation, _Abore_ and _Below_, were evaluated on a separate day, where a subset of 8 participants (1 female) from the full pool did the test. This group had an average age of 37.5 years (SD = 9.3).  
The participants were employees of Fraunhofer IIS or the International Audio Laboratories Erlangen at the time of the experiments, and can be considered expert listeners in audio quality evaluations [35]. However, they were not trained in VR-specific listening tests, and they were naive about the specific conditions under examination here. All of the participants reported no hearing impairments and had a normal or corrected-to-normal vision by self-report. All participants provided written informed consent to participate in each session of the experiment.