A State-of-the-Art Review on Acoustic Preservation of Historical Worship Spaces through Auralization

TL;DR

This review synthesizes the state-of-the-art in acoustic preservation of historical worship spaces through auralization, detailing five core components: room acoustic acquisition, sound-field analysis, sound-field synthesis, real-time auralization, and perceptual evaluation. It surveys measurement and modeling techniques for accessible and inaccessible spaces, discusses both loudspeaker- and headphone-based reproduction, and covers real-time processing strategies (including partitioned convolution and delay networks) and feedback-cancellation approaches. The Nassau Chapel case study illustrates a complete pipeline from measurement to real-time auralization and perceptual assessment, demonstrating how such workflows can preserve and valorize historic acoustics for researchers and performers. The article also highlights challenges—computational load, latency, perceptual validity, and interactive tool development—while outlining future directions for broader, more immersive, and validated preservation efforts. These insights offer a concrete foundation for researchers, heritage professionals, and practitioners aiming to safeguard and recreate the sonic character of historical worship spaces.

Abstract

Historical Worship Spaces (HWS) are significant architectural landmarks which hold both cultural and spiritual value. The acoustic properties of these spaces play a crucial role in historical and contemporary religious liturgies, rituals, and ceremonies, as well as in the performance of sacred music. However, the original acoustic characteristics of these spaces are often at risk due to repurposing, renovations, natural disasters, or deterioration over time. This paper presents a comprehensive review of the current state of research on the acquisition, analysis, and synthesis of acoustics, with a focus on HWS. An example case study of the Nassau chapel in Brussels, Belgium, is presented to demonstrate the application of these techniques for the preservation and auralization of historical worship space acoustics. The paper concludes with a discussion of the challenges and opportunities in the field, and outlines future research directions.

Figures (7)

• Figure 1: Overview of an auralization process for the preservation and reproduction of . The process consists of five main components: room acoustic acquisition, sound field analysis, sound field synthesis, real-time auralization, and perceptual evaluation. The dark-colored boxes represent the relevant methods for each component. The components and their corresponding methods can be utilized either in combination or individually as tools to preserve and reproduce the acoustics of . All components and methods, together with their application to the preservation of historical worship space acoustics, are discussed in detail in the following sections.
• Figure 2: Magnitude of spherical harmonics up to order $N=3$. Light regions represent positive sign values, while dark regions represent negative sign values. The radius indicates the magnitude of the spherical harmonic.
• Figure 3: Block diagram of a real-time auralization system containing $L$ loudspeakers and $P$ microphones. The microphone signals are first preprocessed by a conditioner function $\mathbf{G}$, after which they are convolved with the synthesis filters $\mathbf{H}$ to create the synthesized sound field. Acoustic feedback cancellation is implemented using the multichannel feedback path estimate $\mathbf{\hat{F}}$ and subtracting the resulting feedback signals from the microphone signals, to compensate for the acoustic feedback path $\mathbf{F}$.
• Figure 4: (a) View from the chapel floor looking towards the choir loft. (b) View from the choir loft looking onto the chapel floor. The loudspeaker used during the acoustic measurements is positioned on the right side of the choir loft.
• Figure 5: Floor plan of the Nassau Chapel containing the microphone array positions, denoted as circles, and the loudspeaker positions, with the direction of the loudspeaker indicated by the triangle. Two sets of measurements were taken: one with the loudspeaker on the left side of the choir loft (light gray), and the other with the loudspeaker on the right side of the choir loft (dark gray). The microphone array positions were positioned around each loudspeaker position in the choir loft. The microphone positions in the chapel floor are common for both sets of measurements. The measurements are labeled X$1$ to X$10$ for measurements made using the left-side loudspeaker and Y$1$ to Y$10$ for the right-side loudspeaker.