Whistling buildings: wind-induced noise
Wind-induced noise in buildings can cause significant noise disturbance for both the occupants inside and the community outside. Broadband noise caused by turbulent flow over bluff features is not generally a problem, but whistles or hums (i.e. tonal noise) can be very obtrusive.
Tonal wind noise is normally associated with acoustic resonances of cavities or structural resonances of flexible components, giving rise to feedback mechanisms in the vortex-shedding process. These resonances create the architectural equivalent of a musical instrument, such as a flute or an Aeolian harp, which generate a tone at particular wind speeds and directions.
There are so many possible mechanisms that guaranteeing to eliminate to all problems at the design stage on a large development is impossible in most cases, although ISVR Consulting can provide design guidance. One case that can be predicted is where large areas of louvre screen or other regular features are planned, in which case simple calculations can be made to ensure that vortex shedding frequencies do not coincide with natural frequencies of vibration. Wind tunnel testing of mock-ups can also help to minimise risk.
Besides helping at the design stage, ISVR Consulting can assist in resolving existing problems by identifying source mechanisms and suggesting and testing solutions.