Tuning acoustical facade designs aiming for a controlled influence on the urban soundscape

Abstract

The representative high-rise facades of today's major cities are composing urban spaces out of glass and steel. With the reflection of one noise source on one hard reflective facade the noise level in an urban space can increase up to 3 dB. In the case of multiple reflections in a complex urban setting the level can increase up to 8 dB. Taking this effect into account, the surfaces of inner city facades have to be redesigned aiming for absorption of the sound energy. Due to the different functions of a façade, e.g. vista, light, energy and air, the complete covering of a facade in order to gain broadband absorption is not feasible. If the targeted broadband absorption is not feasible, the absorption effect can be tuned to several frequency bands in order to transform the uncomfortable noise perception into a comfortable one. During this research facade designs were developed with a focus on the acoustical effectiveness. It was demonstrated, that with a tunable acoustical facade construction, more than one frequency band can be influenced, thus achieving a comfort soundscape in an urban space.