Method for conducting an on-site measurement of a density value of an insulation material is provided, comprising: (a) providing an acoustic source for emitting a sound wave; (b) directing the sound wave emitted from the acoustic source through a waveguide and at an insulation material present in a wall, floor or ceiling cavity; (c) measuring a sound pressure in the waveguide to obtain at least one sound pressure measurement; and (d) calculating a density value of the insulation material based on the at least one sound pressure measurement.