Maureen Connelly

Laboratory experimental investigation of the acoustical characteristics of vegetated roofs.

A laboratory‐based experimental investigation was made of the sound‐absorption and sound‐transmission characteristics of vegetated roofs and/or their components. Impedance‐tube measurements of the normal‐incidence absorption coefficients of different substrates were related to their physical characteristics, finding that percentage organic matter, volumetric water content, and compaction are the key influencing factors. Spherical‐decoupling‐method measurements of the normal‐incidence absorption coefficients of different thicknesses of substrate without and with vegetation showed that the absorption of substrates tends to increase with frequency, substrate depth, and to decrease with moisture content and vegetation. Sound‐intensity measurements of the green roofs with different thicknesses of dry or wet substrate without and with vegetation, made in a purpose‐built facility, showed that transmission loss increased rapidly with frequency, and increased with substrate depth and water content.

Empirical measure of absorption and scattering properties of living wall plants and systems and predictive modeling of room acoustic benefits

This series of research projects investigate the acoustical characteristics of interior living walls and predicts how they can be used to positively benefit room acoustics. Scaled and full scale evaluations were executed in a reverberation chamber to validate test methods for absorption and scattering coefficients of soil/substrate and plant species (characterized by height, stem diameter, mass, leaf geometries and dimensions, and leaf area index (LAI)). Wall systems were evaluated over a gradient of plant coverage with monoculture and community planting. Evaluation indicates that evenly distributed pumice can act as the baseline on the scattering turn-table in a method to evaluate scattering coefficients of plant-specific foliage. Findings indicate that percentage of plant coverage is related to absorption coefficients (0.16–1.1) as averaged across all evaluated species. Only at low plant coverage do specific plant characteristics affect the absorption coefficients. The percentage of plant coverage is re...

Acoustical evaluation of residential laneways and laneway housing

Laneway housing (LWH), a free-standing, small wood-frame house (1 to 1.5 stories high and less than 900sf in floor area), is an increasingly popular product of Vancouver B.C.’s high-density urban growth policy. LWH is subject to multiple noise concerns due to its small architectural form and siting in laneways typically designed for garage access and utilities. (Laneways are approximately 16 ft wide and 12 to 18 ft high.) Case study investigations examined residential laneways as potential urban canyons and the acoustical performance of LWH envelope. Methods employed include ASTM field measurements, software models (Odeon and AFMG Soundflow), and the National Research Council of Canada traffic noise model (comparable to the FHWA model). Metrics evaluated include rate of attenuation over propagation distance through a laneway, facade transmission loss, and room absorption. Results show that certain laneways function as urban canyons, measuring nearly 20 dBA higher in SPL at the LWH facade than in laneways ...