Models for acoustical properties of green roof materials

Attenborough, Keith; Bashir, Imran; Taherzadeh, Shahram and Hill, Toby (2011). Models for acoustical properties of green roof materials. In: Forum Acusticum 2011, 26 Jun - 01 Jul 2011, Aalborg, Denmark.


To predict the acoustical effects of green roof structures it is necessary to be able to model the acoustical properties of their materials including gravel. For time domain calculations it is convenient to use the phenomenological model due to Zwikker and Kosten. However this phenomenological model is related to a low frequency/high flow resistivity approximation of more ‘exact’ identical pore models. The results of fitting predictions to short range level difference data and to impedance data for gravel indicate that the Zwikker and Kosten model does not perform as well as other models for low flow resistivity surfaces. For frequency domain calculations of sound propagation over extensive green roofs other models should be more accurate. For time domain calculations use of a two-parameter version of a relaxation model is recommended.

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