The invention provides a sound attenuating panel (100) with controllable sound attenuation properties, the sound attenuating panel (100) comprising (a) a sound attenuating unit (200) with cavities (212) with variable dimensions and (b) an infrastructure (300) for controlling the dimensions of the cavities (212) in the sound attenuating unit (200). The sound attenuating unit comprises sound attenuating material with controllable sound attenuating properties, but may also have wave guiding properties, thereby allowing to combine in the sound attenuating unit 200 both sound attenuating properties and optical properties.