## 7 Conclusions  
Alongside realistic graphical rendering and natural approaches to computer interaction, spatialized audio can be used to significantly enhance presence and improve user interaction within a virtual reality environment [76]. In terms of clinical applications within autism research, presenting a more realistic experience would benefit interventions such as the treatment of phobias and vocational training. By matching the visual and auditory sensory experiences of the real world, users will have a greater chance of generalizing newly acquired skills into their everyday lives, therefore increasing the possible positive outcomes of VR-based therapy [77].  
To date, this study is the first to assess how those with autism respond to virtual spatial audio within a virtual reality game environment. The experiment involved 29 individuals diagnosed with autism being randomly allocated to 3D audio and mono control groups. All participants completed two experimental phases. The first compared spatial attention towards auditory stimuli by recording head rotation accuracy and horizontal movement towards presented audio. In Phase Two, participants were required to localize four social and four simple stimuli among varying levels of background audio. Results collated from head rotation and tracked positional data during the experiment do suggest that despite reported auditory processing difficulties, children with autism can make use of auditory cues rendered by spatial audio. In addition, the amount of background audio can have significant effects on the localization of auditory stimuli within a VE. These findings could provide valuable insight to those designing virtual reality interventions for the autistic population. Possible developers should make use of similar binaural-based spatial audio rendering approaches used in this study to increase the ecological validity of the virtual environment, deliver important information via auditory cues.  
This study has shown that previously reported difficulties in auditory scene analysis associated with autism do extend into the realms of virtual reality and binaural-based spatial audio. The amount of competing background audio can have an effect on spatial attention towards virtual sound targets and so therefore this should be taken into consideration when designing three-dimensional virtual acoustic environments for ASD interventions.  
Conceptualization, D.J. and G.K.; Methodology, D.J.; Software, D.J.; Validation, D.J., H.E. and G.K.; Formal Analysis, D.J., H.E.; Investigation, D.J.; Resources, D.J.; Data Curation, D.J.; Writing--Original Draft Preparation, D.J.; Writing--Review & Editing, D.J., H.E. and G.K.; Visualization, D.J.; Supervision, H.E. and G.K.; Project Administration, D.J.; Funding Acquisition, G.K. Funding Funding was provided by a UK Engineering and Physical Sciences Research Council (EPSRC) Doctoral Training Award, via the Department of Electronic Engineering at the University of York, EPSRC Grant Number: EP/N509802/1.  
The authors would also like to thank Accessible Arts & Media (York, UK), Springwater School (Harrogate, UK) and Riverside School (Goole, UK) for their participation and support of this research.  
The authors declare no conflict of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data, in the writing of the manuscript, or in the decision to publish the results.  
The following abbreviations are used in this manuscript:  
\begin{tabular}{l l} ASD & Autism Spectrum Disorders \\ CVE & Collaborative Virtual Environment \\ HMD & Head Mounted Display \\ SNR & Signal-To-Noise Ratio \\ TD & Typically Developed \\ VE & Virtual Environment \\ VR & Virtual Reality \\ \end{tabular}