Introduction & Project Overview
Located in Curitiba, Paraná, Brazil, the São José e Santa Felicidade Parish, build in 1891, is a historic religious landmark characterized by its traditional architecture and highly reverberant acoustic environment. While visually impressive, the church’s large internal volume and reflective surfaces created substantial challenges for speech intelligibility during liturgical celebrations.
Due to strict architectural preservation requirements, conventional passive acoustic treatments such as absorptive panels or architectural modifications were not viable options. The project therefore focused on developing an advanced electroacoustic solution capable of significantly improving verbal communication while fully preserving the church’s historic identity together with an optimized cost-effectiveness through partial reuse of the existing sound system infrastructure.
A comprehensive acoustic study was conducted using detailed computational modeling and in-situ acoustic measurements. Acting as the project's acoustic consultant and lead designer, PROECO - Acoustics & Vibrations developed a detailed 3D model of the church in EASE 5, incorporating the absorption and scattering coefficients of all relevant construction materials present in the venue. The modeled environment comprised a total volume of 4,273 m³ and a modeled surface area of 2,326 m².
Simulation and analysis of key acoustic parameters was performed through AURA Mapping, enabling precise evaluation of speech intelligibility and sound coverage throughout the audience. Different project stages were employed to evaluate multiple sound system configurations and optimize system performance.
Key acoustic parameters analyzed included:
- T30 (Reverberation Time)
- STIPA (Speech Transmission Index for Public Address Systems)
- Direct Sound Pressure Level (Direct SPL)
- Sound coverage uniformity
Challenge
The architectural characteristics of the church created a highly reverberant environment that negatively affected speech intelligibility. Initial acoustic measurements revealed excessive reverberation times, particularly within the frequency range between 250 Hz and 1000 Hz, relevant to speech communication.
Baseline STIPA measurements ranged from 0.28 to 0.35, classified as “Poor” according to international speech intelligibility standards. The highly reverberant environment significantly reduced speech intelligibility, limiting the effectiveness of spoken communication throughout the church.
The existing sound reinforcement system further contributed to the problem, exhibiting:
- Low predominance of direct sound field
- Irregular sound coverage
- Acoustic shadow zones
- Poor SPL uniformity across the audience area
Compounding these technical challenges were strict architectural limitations that prohibited substantial passive acoustic interventions. The solution therefore required a highly precise electroacoustic strategy capable of overcoming the room’s natural reverberant behavior without altering the architectural character of the venue.
Project requirements included maximizing cost-effectiveness through the strategic reuse of existing loudspeaker infrastructure wherever technically feasible
Project Execution & Results
Acoustic Assessment and Model Development
The project began with detailed acoustic measurements at eight locations throughout the main nave to gain a clear understanding of the church's existing acoustic conditions. These measurements also provided the basis for validating the acoustic simulations used during the design process.
A detailed three-dimensional model of the church was then created in EASE 5, incorporating both the building geometry and the acoustic properties of the materials present in the space. The model was calibrated using the measured T30 values to ensure close agreement between the simulations and the actual acoustic behavior of the church.
With a validated model in place, the project team was able to confidently evaluate different sound system concepts and predict their impact on speech intelligibility and sound coverage before implementation.
Simulation-Based System Optimization
Multiple design scenarios were investigated to determine the most effective solution for the church's acoustic challenges. Various configurations were analyzed, including changes to:
- Loudspeaker positioning
- Installation heights
- Number of loudspeakers
- Loudspeaker types and coverage characteristics
Using AURA Mapping, the project team performed detailed spatial analyses of STIPA and SPL distribution across the audience area. These simulations made it possible to identify regions with reduced intelligibility or insufficient coverage and to optimize the system design accordingly.
The simulation-driven approach enabled objective comparison of alternative solutions while ensuring compatibility with the architectural constraints of the historic building.
From Simulation to Implementation
Based on the simulation results and regarding the project's requirements and restrictions, a final loudspeaker configuration and delay strategy were developed and implemented throughout the church.
The final implementation included:
- Repositioning of existing Bose MA-12 loudspeakers
- Repositioning of existing JBL CBT-100LA loudspeakers
- Addition of four new JBL CBT-100LA loudspeakers
- Installation of JBL CBT-50LA loudspeakers in the presbytery
- Application of a distributed delay strategy for the CBT-50LA loudspeakers, with delay times ranging from 18.7 ms to 58.3 ms to synchronize arrivals between loudspeaker zones and reinforce direct sound throughout the nave.
This configuration was selected after evaluating multiple loudspeaker layouts and installation scenarios. In addition to optimized loudspeaker placement, the delay settings were carefully tuned to improve temporal alignment between coverage zones, minimizing perceptual echoes and enhancing speech clarity. The final design achieved more uniform sound coverage throughout the nave, increased direct sound energy at listener positions, and significantly improved speech intelligibility while remaining visually unobtrusive within the historic interior.
Acoustic Improvements and Project Results
The measured STIPA value increased from approximated average of 0.31 to an average of 0.47, representing a major enhancement in speech clarity within an extremely reverberant environment. Sound coverage uniformity was also significantly improved, with 95% of the audience area maintained within the target range of 66 ± 3 dB.
The project additionally demonstrated excellent correlation between simulated and measured acoustic results, validating the high predictive accuracy of EASE 5 computational modeling for complex environments.
Most notably, the case proved that meaningful intelligibility improvements can be achieved even in architecturally sensitive spaces where passive acoustic treatment is not possible. Through precise electroacoustic engineering, advanced simulation methodologies, and optimized loudspeaker deployment, the São José e Santa Felicidade Parish now benefits from significantly improved speech communication while fully preserving its historic architectural character.
This project stands as a strong example of how modern acoustic simulation tools and intelligent sound system design can successfully address the demanding challenges of highly reverberant sacred spaces.
