Effects of ceiling phase gradients on the acoustic environment on roadside balconies

The screening effect of a roadside balcony deteriorates considerably due to sound reflection from its ceiling. Nonetheless, this drawback can be eliminated by artificially steering the reflected sound away from the building facade, which is achieved by introducing impedance inhomogeneity to the ceiling surface. This paper presents an elaborated investigation on the effect of the phase gradient of a ceiling surface on screening exterior noise, theoretically and numerically. By balancing its sound-steering capability and performance fluctuation level, such a balcony ceiling may have the potential to be widely used on roadside buildings.