Measurement of the sound absorption characteristics of vegetative roofs

Connelly, Maureen (Maureen Connelly (Maureen_Connelly)) (author)
Hodgson, Murray (author)
(editor)
(translator)

© 2010 Maureen Connelly and Murray Hodgson

Vegetative roofs have the potential to provide excellent external/internal sound isolation due to their high mass, low stiffness and their damping effect, and to provide a high level of sound absorption due to the low impedance of the vegetative substrate layer. The acoustical characteristics of vegetative roofs provide ecological contributions to the urban environment through a reduction of noise pollution from aircraft, elevated transit systems, and industrial noise. Vegetative roofs can reduce sound transmission into the interior of buildings, contributing to improved room acoustics through a reduction in noise and hence a reduction in distraction and stress (Connelly & Hodgson 2008). Through surface absorption, vegetative roofs will affect the propagation and build-up of positive and negative sounds and reduce reverberation in enclosed rooftop areas, altering the quality of the soundscape and the habitability of rooftops. Vegetative roofs can be comprised of various material layers: root barrier, water reservoir/drainage layer, filter fabric, substrates and plants. The layer thought to have the most significant effect on the vegetative roof’s acoustical characteristics is the layer of the vegetation and substrate. The vegetative substrate is complex to characterize; it varies in terms of the depth of substrate, the substrate constituents and physical properties, the plant’s aerial biomass and root structure, as well as the dynamic in-situ microclimatic and conditions which vary over season and time.

https://jcaa.caa-aca.ca/index.php/jcaa/article/view/2289/2037