**4.5 Additional observations**

There were some additional results on factors and measures which were not explicitly asked for by the RQs:


*The Influences of Hearing and Vision on Egocentric Distance and Room Size Perception… DOI: http://dx.doi.org/10.5772/intechopen.102810*

acoustic condition to be more consistent with—and in the case of room size, even more accurate than—those under the visual and acoustic-visual conditions. Therefore, when visual information is unavailable, perception may exploit the greater amount of acoustic information provided by low-absorbent rooms to improve the accuracy of room size perception. Acoustic absorption may influence not only the values but also the availability and/or acuity of auditory cues (cf. 1.2).

Observations (d) and (e) and differences between the studies regarding domain proportions (4.3) give reason to hypothesize that structural and material properties of rooms influence distance perception. Thus, an additional experimental dissociation of the factors physical source distance, physical room size, and acoustic absorption (all else being equal) might be instructive. Furthermore, more detailed physical factors affecting both the acoustic and the visual domain might be disentangled (primary structures, secondary structures, materials). Because of the trade-off between the requirement of ecological stimulus validity and the costs of stimulus production, it might be worth investigating the moderating effects of certain aspects of virtualization (direct rendering, stereoscopy, visually moving persons). In the future, one major aim of research into the perception of geometric properties might be the connection of the modeling of internal mechanisms and the physical-perceptual modeling.
