## 4 Results and Discussion  
### Results of Grouping for Auditory Evaluation Factors  
From the primary expert interviews, the auditory evaluation factors identified in the literature review were grouped and are presented in Table 7.  
As shown in Table 7, the factors of 'the concentration of contents due to hearing' [22], and 'presence with or without auditory backgrounds' [34] were grouped as 'focusing the metaverse environment with sound' because they are classified as the same concept of'sense of presence' in the reviewed literature [32; 34; 44]. The factors of 'the spatial characteristics of sound' [14],'spatialized sound' [43],'spatialized sound source' [44], and binary audio (spatial acoustics) [45] were grouped into 'implementing the spatial properties of sound' because they use the common concept of'space' according to P1's opinion. 'Similarity to real-world sounds [34],'realization of real sounds' [39],'reproduction of soundscapes' [40], and 'everyday soundscapes' [41] were grouped as 'implementing realistic soundscapes in a metaverse environment' because they use the common auditory concept of'real soundscapes' according to P1's opinion. 'Perceived location factor of sound' [22], three-dimensional spatial representation of sound [39], and 'three-dimensional representation of sound' [42] were grouped into 'three-dimensional perception of sound' because they use the common concept of 'location' according to P2's opinion. \begin{table}
\begin{tabular}{c c c c c c} \hline
**Participants** & **Gender** & **Age** & **Work History** & **Activity Industry** & **Profession/Occupation** \\ \hline P4 & Male & 31 & 6 years & Doctoral graduate students & Music educator and sound designer \\ \hline P5 & Female & 33 & 3 years &
\begin{tabular}{c} Music therapy practice in a \\ university hospital \\ \end{tabular} & Music therapist and composer \\ \hline P6 & Male & 32 & 7 years & Game company & Sound designer \\ \hline P7 & Female & 31 & 10 years & Healthcare company & Composer and sound designer \\ \hline P8 & Male & 26 & 3 years & Consumer electronics company & Composer and sound designer \\ \hline \end{tabular}
\end{table} 
Table 6: Participant information from Step 2. The factors of 'good sound' [19], 'interesting sound' [19], 'boring sound' [19], 'unpleasant sound' [53], 'wanting to stay again' [54], and 'unpleasant sound' [54] were grouped under the common term 'willingness to return due to sound' because of their common meaning of measuring the impression of sound, according to all expert opinions. The factors of 'quality of sound' [14],'sound source quality' [39], 'degree of sound echoing' [53] 'degree of sound softness' [53], 'loudness of sound' [53; 54], and 'keeping sounds short and smooth' [57] were grouped into 'the quality of the sound source' because they use the common auditory concept of 'quality of sound' according to P2's opinion. The factors of 'how confusing it is to hear the sound' [19], 'distractions from noise outside the metaverse environment' [36], and the 'attracting attention without being distracting' [57] can be grouped into 'how distracting the sound is' as they use the common auditory concept of 'distraction' according to P1 and P3's opinions.