A method of installing an acoustical system that provides a desired sound attenuation includes attaching an acoustical panel having a first density, a first porosity and a first void volume to the substrate. A first finishing layer is prepared with first particles, a first binder, a first rheological modifier and water which are combined, applied to the substrate and dried. The first finishing layer has a first density. When the first sound attenuation changes to a second sound attenuation a second finishing layer is prepared to include second particles, a second binder, a second rheological modifier and water. The dried second finishing layer has a second density. If the second density is less than the first density, the second sound attenuation is greater than the first sound attenuation. If the second density is greater than the first density, the second sound attenuation is less than the first sound attenuation.