A comprehensive assessment of room acoustics to achieve acoustic comfort: a case study of retrofitting for speech intelligibility in a residential space

Abstract

This paper aims to demonstrate through a case study, a comprehensive assessment of the acoustics in an indoor residential space where the occupants expressed discomfort due to echo experienced causing low speech intelligibility under certain conditions and to identify and optimize appropriate acoustic treatment solutions to tackle the issue. To this end, the space was studied for its geometry and materials, a simulation model was developed and calibrated through field measurements. To identify acoustic solutions to the problem, the impact of room geometry and baseline materials were studied. For the given room geometry, the Schroeder frequency and dominant room modes were identified. Following this, suitable high-performing sound absorbers were identified for retrofitting. The minimum absorption area required by the materials and their optimal configuration in the space were determined through iterative studies. Reverberation Time (RT), and spatial variation of the Early Decay Time (EDT) and Speech Transmission Index (STI) were studied for each acoustic configuration and compared with the baseline state to arrive at an optimal solution. At its baseline state, the acoustic performance of the space studied showed an RT = 2.6 s, EDT = 3.1 s, and STI = “Poor”. With the optimal acoustic solution installed, the acoustic performance of the space was predicted to have an RT = 0.69 s, EDT = 0.7 s, and STI = “Excellent”. The predicted reverberation time was validated through field measurements of RT. This 3.8X improvement in the acoustic performance can be attributed to the sound absorbers which were estimated to contribute to 68% of the sound absorption in the acoustically treated room. This study shows that an integrated and holistic approach to understanding the interplay of acoustics, architecture, human perception, and wellbeing is key for designing strategies for acoustic comfort.