## 2 Literature Review
### Auditory Evaluation Factors in the Presence Evaluation Questionnaire for a Metaverse Environment  
Since most of the evaluations of auditory presence in metaverse environments are technical evaluations of engineering sensors, and it is difficult to find data in the form of questionnaires for auditory presence evaluation, a literature review of auditory evaluation factors was first conducted in general presence evaluation questionnaires. In order of development date, the reviewed questionnaires include the presence questionnaire (PQ), the Slater-Usoh-Steed presence questionnaire (SUS-PQ), the reality judgment presence questionnaire (RJPQ), the group presence questionnaire (IPQ), the Independent Television Commission sense of presence inventory (ITC-SOPI), the engagement, enjoyment and immersion questionnaire (E2 IQ), and the measurement, effects, conditions spatial presence questionnaire (MEC-SPQ). PQ categorizes presence into three characteristics: involvement, immersion, and presence, and emphasizes sensory stimulation, participation, immersion, and interaction. The auditory presence evaluation factors include QN 6 (How much did the auditory aspects of the environment involve you? ), QN 15 (How well could you identify sounds? ), and QN 16 (How well could you localize sounds? ), which are all about presence [22]. SUS-PQ assesses the sense of presence, which is the degree to which a person feels that he or she exists in a virtual environment rather than in an actual physical space. In particular, the degree to which a person is convinced that fictional information is real is viewed as presence, and it measures the degree of presence caused by the relevance of the user and the avatar. SUS-PQ consists of five evaluation factors: the experience and degree of 'being there', a comparison of virtual and real images, the association of the visual structure of the virtual environment, and the frequency of detecting virtual reality [32; 33]. RJPQ categorizes presence into nine dimensions: reality judgment, presence, involvement, interaction, control, attention, realism, perceptual congruence, and expectations in virtual environment, and emphasizes natural interaction. The auditory presence dimension consists of three questions: QN 4 (How clear were the sounds in the virtual world?) on realism, QN 73 (To what extent did what you hear and the quality of the sound in the virtual world influence how real the experience seemed to you?) on reality judgment, and QN 76 (To what extent did the sounds influence how deep into the virtual world you went?) on presence [34]. IPQ categorizes presence into three factors: spatial presence, involvement, and realism, and covers a wide range of subjective experiences, immersion, and interaction, with no questions related to hearing [25]. ITC-SOPI categorizes the sense of presence into four factors: sense of physical space, engagement, ecological validity, and negative effects, and finds that not only the implementation of the physical environment, but also the overall usability, such as the attractiveness, naturalness, and trustworthiness of the content, could affect the sense of presence, and there are no questions related to hearing [35]. E2 IQ categorizes the sense of presence into six factors: the sensory factor, distraction factor, realism factor, control factor, pleasure factor, and satisfaction factor, and considers various UX aspects such as the attractiveness of the visual scene, the degree of distraction caused by noise outside the device, the realism and consistency of the sensation of virtual movement, and the immersion of the task. The auditory dimension is covered by QN 2 (To what extent did events such as noise occurring outside Crayolaland distract your attention from Crayolaland? ), which is about distraction [36]. MEC-SPQ approaches the evaluation of presence from a UX-centered perspective rather than a technology-centered perspective, and its contents are important for redefining spatial presence, which has not been systematically addressed in existing studies.