Presence is used to assess the subjective experience of being in one place when physically situated in another. Recently, the research on presence has gained increasing attention due to the wide use of immersive audio technologies. Currently, the most widely-used measurement of presence is based on post-experiment self-report questionnaires. It is reliable but imperfect due to the psychological changes caused by the act of answering the questionnaire when immersed in the virtual environment. Therefore, the present work aims to find an objective way to measure presence, and electroencephalography (EEG) was investigated as a possible tool for this objective measurement. In this study, two listening tests were conducted, where eight loudspeakers were used to reproduce urban soundscapes to stimulate auditory presence. Presence was measured by both questionnaires and EEG. Results showed a significant correlation between T/B (Theta/Beta Ratio) extracted from EEG and subjective presence levels assessed by questionnaires, suggesting the possible use of EEG to measure presence objectively. This study could bring some insight for the research of presence, and related technologies, such as VR, video games and immersive audio production.

Presence is the sense of being in a virtual environment when physically situated in another place. It is one of the key components of the overall virtual reality (VR) experience, as well as other immersive audio applications. However, there is no standardized method for measuring presence. In our previous study, we explored the possibility of using electroencephalography (EEG) to measure presence by using questionnaires as a reference. It was found that an increase in the subjective presence level was correlated with an increase in the theta/beta ratio (an index derived from EEG). In the present study, we re-analyzed the original data and found that the peak alpha frequency (PAF), another EEG index, may also have the potential to reflect the change in the subjective presence level. Specifically, an increase in the subjective presence level was found to be correlated with a decrease in PAF. Together with our previous study, these results indicate the potential use of EEG for the objective measurement of presence in the future.

The program material is of great importance for the results of the listening tests on loudspeakers, while the process of how to select the program material remains ambiguous. This paper investigates the criterion for selecting programs suitable for low-frequency perceptual evaluation based on the audio features of the program. A listening test was conducted to identify the more discriminating and revealing programs in the low-frequency range. Based on the listening test results, various characteristics of the programs, including dynamic, timbral, rhythmic, and spectral features, were extracted. Their relationships with the program’s discrimination ability are discussed. The results suggest that programs with a slow and clear rhythm and a smooth and even spectrum in the whole band are more discriminating in detecting the spectral differences in the low frequencies. By using these significant features, a discriminant analysis was performed to predict the ability of the program to reveal the spectral irregularities. The predictive accuracy of the derived discriminant function was 95% in separating the discriminating and undiscriminating programs.