Noise and Acoustics

Understand, analyse and mitigate for all types of noise and acoustic issues. Xi Engineering Consultants use a variety of methods to model noise and acoustics.  The modelling approach depends on the specifics of the project, principally the size of the acoustic domain relative to the minimum wavelength which is being modelled. 

Another important consideration in designing a modelling approach is understanding the nature of the output required and its subsequent use.  When the size of the acoustic domain is comparable to the wavelength of the sound being modelled then finite element (FE) analysis is favoured.  An example of this modelling is the low-frequency response of a headphone speaker where the wavelength and acoustic domain are both centimetre scale.

In situations where the acoustic domain becomes large with respect to the wavelength, it is necessary to use other approaches to model the sound field.  Boundary element method (BEM) provides a means to model large structures without requiring large numerical meshes, which are a requisite for FE.  An example of the used of BEM is the modelling of the acoustic output of wind turbines with 200 m tip heights and their effect on local communities.  Ray tracing and parametric equation approaches are also an efficient way to model the propagation of noise for point and linear sources, such as motorways and construction activity.  Xi also use ray tracing and parametric equation approaches for modelling building acoustics, such as concert hall acoustics, and underwater noise and its impact on marine species.  A diffusion equation approach is a very effective way of modelling acoustics of coupled rooms within a building, the results of which can be used to improve office and residential environments.