Digital Culture & AudioVisual Challenges

This study evaluates the effectiveness of a multi-layered soundscape topology in recreating auditory environments through an ex-situ experiment. The aim is to understand the dynamic of these soundscapes and assess the impact of using personalized spatial cue on user experience and immersion.

The term 'Soundscape' was introduced in 1969 (Schafer, 1969) and has since become a critical area of scientific research and creative exploration. It has been found that auditory displays have a greater impact on human mood and well-being than visual elements, as they can influence perception and evoke emotional responses (Jiang et al., 2021). As a result, audio-walks and virtual tours utilize soundscape design to provide immersive exploration and insights into diverse auditory environments around the world from the convenience of one's home (Boren et al., 2014). To achieve perceptual similarity to real-world experiences, it is necessary to realistically recreate auditory scenes for ecological validity in soundscape reproduction (Xu et al., 2021). Virtual and Augmented Reality technologies have the potential to enhance laboratory assessments, leading to improved acoustical quality (Dedousis & Andreopoulou, 2023; Li & Lau, 2020).

The introduction of ISO 1291301:2014 has significantly advanced soundscape research by addressing the complexities of collecting in-situ subjective soundscape assessments. Ex-situ, laboratory-based evaluation methods have also being explored (Jo & Jeon, 2021). Spatial audio technologies are noted for their ability to provide improved experimental control in such cases (Aletta & Xiao, 2018), although they may introduce artifacts that differ from real-world perceptions (Tarlao et al., 2022). Binaural reproduction (Skoda et al., 2019), particularly when combined with active head-tracking (Ooi et al., 2017), has been shown to improve the accuracy of perceiving soundscape characteristics, overcoming the limitations of non-individualized HRTFs. The analysis indicates a preference for in-situ experiences due to the additional visual context, while laboratory reproductions are preferred for focused analyses.

The TRACCE project is a mobile application that focuses on designing and creating historically informed soundscapes. The project aims to recreate the auditory environments of specific landscapes from the past, using sources such as travelogues, iconography, sketches, and contemporary photographs (Dedousis et al., 2021). Extensive research is required to capture the acoustic characteristics of historical locations, including the selection of audio samples and the composition of abstract musical elements to complement the auditory content.

A multi-layered topology is utilized to create soundscapes for headphone listening, incorporating four distinct yet complementary layers of auditory content. The Background layer reconstructs the primary auditory elements of the landscape, the Storytelling layer introduces binaural reproduction of sounds associated with interactions in the environment, and the Narration layer includes monaural audio tracks with narrated excerpts from original texts. Finally, the Music layer includes binaural electroacoustic compositions based on stochastic interpretations of the remaining layers, ensuring seamless integration of the most prevailing auditory elements.

The aim of this study is to assess the effectiveness of the utilized soundscape topology and the design choices made for the composition of the historically informed soundscape content, through an ecologically valid ex-situ evaluation experiment. The importance of using personalized binaural cues for user immersion in this context is also evaluated. 25 individuals evaluated the composed historically informed soundscapes, reproduced by headphones, while experiencing contemporary real-world soundscapes played back via a periphonic 8-speaker arrangement in an acoustically controlled listening environment. Results showed accurate identification of sound sources and successful isolation of auditory content. For example, participants identified sounds of a sea soundscape, but sometimes confused them with the sound of running water. Correlations were assessed between historically informed and contemporary soundscapes, and were generally found to be average to good. However, the results were influenced by some modern-day sounds (e.g., garbage trucks), differences in seasons, and changes to the landscape. Furthermore, the analysis showed that personalized Head-Related Transfer Functions (HRTFs) had an impact on the listeners' immersion as far as the soundscape design was concerned but did not significantly augment one’s experience regarding complementary auditory features (such as musical content).

The study demonstrated the feasibility of ex-situ evaluations for ecologically valid soundscape assessments. This emphasizes the importance of ex-situ evaluation methodologies in studying soundscapes, particularly in controlled laboratory environments. Ecologically valid methodologies can be developed for evaluating soundscapes by using immersive audio technologies and historical data, which can provide new insights into understanding and experiencing the world through sound. Future work includes larger-scale experiments with diverse participant demographics and dynamic rendering of immersive soundscape designs to validate these findings.