Auditory Impressions of a Small Wooden Music Venue Repurposed from a Non-Musical Facility in Historical Landscape: A Case Study of the Opera House Omoriza

In Japan's historical regions, particularly those designated as World Heritage sites, maintaining the use of existing buildings while preserving the traditional landscape has become an urgent task. Recently, there has been a growing trend of repurposing wooden structures for new functions-for example, converting them into small music venues. One such case is the opera house Omoriza, a former post office that has been transformed into a unique music facility. What sets Omoriza apart is that its exterior, a valuable World Heritage building, has been carefully preserved. However, since it was not originally designed for musical performances, its acoustic performance remains a challenge. In particular, Omoriza's asymmetrical layout and the close proximity of some seats to the walls create variations in the strength and direction of early reflected sound at different seating positions. To better understand these acoustic characteristics, this study conducted two experiments: an acoustic measurement to analyze sound arrival directions and a perceptual experiment to examine the auditory impressions unique to small music venues. The results revealed significant directional variations in sound energy, especially in the low-frequency range of early reflections (0-25 ms), which had a noticeable impact on auditory perception.