This work presents the research framework and the investigations of the acoustical characteristics of interior living walls and their impact on room acoustics. The overall goal is to determine how living walls can be used to positively benefit room acoustics by reducing reverberation and ambient noise, and affect speech intelligibility by creating sonic subzones within rooms.

A method of evaluation at one-third scale was developed to measure the scattering effects of substrates and plant species (Bolbolan). A series of measurement were carried out to quantify the absorption of living walls with consideration of the parameters of carrier type, substrate, moisture content and plant species variants and to determine which parameters most significantly impact the absorption and scattering of living walls (Akbarnejad). The research on the verification of effect of interior living walls on room acoustics includes field measurement experiments of permutations of living walls installed in a 132 m² theater designed for interactive workshops (Daneshpanah); classroom acoustic criteria such as background A-weighted noise, noise criteria (NC) curves, reverberation time, and speech intelligibility are measured and modelled for a 60 m² seminar classroom with varying living wall installations.

Measurement determined that the scattering coefficient of living wall substrate meets the ISO 17497-1 criteria for the turning table base plate. This allowed six living wall plant species, English Ivy, Fern, Golden Pothos, Pilea, Spider plant, Ficus pumila, to be further evaluated in substrate. The function of ‘leaf area index X mass’ was found to be more relevant than plant foliage characteristics (height, stem diameter, mass, leaf thickness, leaf length, leaf area) in predicting absorption; overall coverage is relevant to high-frequency scattering. Living walls reduced reverberation time and may affect speech intelligibility in close proximity to the living wall as measured and modelled in the classroom application.