NUMERICAL MODELING OF THE SOUND FIELD NEAR A TALL BUILDING WITH BALCONIES NEAR A ROAD

A two-dimensional, boundary element numerical model is used to study t he sound field in the region of balconies in a tall building close to a roadway. The sound pressure level relative to the free field level i s calculated within the balconies on the first four floors, and at pos itions 1 m outside the external facade. The effects of shielding of th e source by the balcony wall are found to be largely cancelled by the strong reflected sound from the ceiling and rear wall of the balcony. The insertion loss resulting from eight different applications of an e fficient sound absorbing material to the building surfaces is calculat ed. It is found that treatment of the ceiling or the rear wall of the balcony is the most efficient in terms of noise reduction, producing v alues of between about 5 and 8 dB for a broad band spectrum characteri stic of A-weighted road traffic noise. The maximum effects obtained fo r a combination of surface treatments is 10 dB. Spectra of the sound p ressure level relative to the free field level are compared for a rece iver position in one balcony and it is observed that the main effect o f an absorbent is to reduce the high frequency resonance peaks. (C) 19 96 Academic Press Limited