## 4 Discussion
### Elicited Constructs
#### 4.3.3 Multi-Dimensionality of Listener Envelopment (LEV)  
Another dominant attribute, Listener Envelopment (LEV) is conventionally defined by the feeling of being surrounded in a reverberant sound field [8; 9]. It is a high-level concept and considered to have a multidimensional nature based on the observations from the current results and the literature. As with ASW, conventional objective measures for LEV include a G-based one (e.g., Late Lateral Energy Fraction (\(LG_{80}^{\infty}\)) [8]) and a binaural-decorrelation-based one (e.g., IACC L3 [9]). The present study elicited the attributes labelled as Perceived Reverch Loudness (PRL) and Apparent Reverch Width (ARW), which also seem to be related to G and binaural decorrelation, respectively. In addition, another main attribute elicited, Reverch Direction is also deemed to be associated with both PRL and ARW, which is discussed more below. From this, it is hypothesised that these three reverberation-related attributes are low-level components of LEV. These attributes have not been reported in previous concert hall studies on spatial impression, which mostly focused on comparing different concert halls in LEV and ASW at similar source-listener distances. [PERSON] et al. [11] elicited various subjective terms to describe perceived characteristics of different concert halls using a multichannel auralisation technique, and found that \"loudness\", \"distance\" as well as \"reverbearance\" were most salient differences perceived between concert halls. [PERSON] et al. [54] observed thatperceived reverberance was significantly affected by the listening level and that loudness-based parameters were efficient in predicting the reverberance. However, in the current study, PRL, ARW and Reverb Direction were elicited in relation to changes in listener position or/and head orientation within a single concert hall. The perception of PRL in this context is particularly interesting, since it is usually understood that the physical level of reverberation would vary little across different positions in a space, and yet differences in \"perceived\" loudness of reverberation were clearly audible. It is not yet possible to establish whether it was a change in listener position, head orientation or both that resulted in a difference in PRL from the result of this elicitation study. This will be investigated further in our future quantitative experiment. However, it is hypothesised tentatively that the PRL perception is mainly due to the binaural unmasking as already described above. Additionally, given the conventional measure of LEV, \(LG_{80}^{\infty}\), it seems logical to hypothesise that reverberation arriving laterally would have a greater contribution to the perceptions of PRL and LEV than that from the same or opposition direction of the source. This hypothesis seems to be supported by [PERSON] [55], suggesting that laterally arriving reflections are more important for the perception of \"room presence\". Furthermore, [PERSON] et al. [56] suggested that reflections arriving between 70 ms and 150 ms after the direct sound and from azimuth angles between 60\({}^{\circ}\) and 150\({}^{\circ}\) produced greater LEV. They also found that reflections arriving between 150 ms and 300 ms after the direct sound and from the azimuth angles between \(\pm\)45\({}^{\circ}\) were perceptually significant in producing running reverberation. This concept, seems to be related to the concept of PRL described in the present study, as a low-level attribute of LEV. ARW, on the other hand, is considered to be related to the directional balance of reverberation and the resulting IACC depending on both listener position and head-orientation. For instance, at P1_0\({}^{\circ}\) (at the central axis, with the listener's head pointing forward), the left and right ears would receive reverberation from both left and right sides of the concert hall with similar energies and times of arrival.