Improvement of the sound insulation of stud walls at low frequencies

© Photo Fraunhofer IBP

Measurement setup to determine the sound insulation of stud walls with periodic point load.

Plasterboard stud walls can be manufactured quickly and cost-effectively, and they can easily be removed again if required. Thus, the layout of the rooms can also be adapted subsequently to a variety of requirements. Furthermore, with respect to structural noise protection, stud walls can be considered equivalent to solid walls – at least with regard to human voice and similar sounds. They have become very popular not only in office and industrial building, but have also increasingly been used in residential building.

However, there is a substantial acoustic problem occurring with stud walls: Due to their double-leaf construction they absorb the noise very efficiently at high frequencies. At low frequencies, though, they provide only low insulation. If two rooms are separated by a stud wall, this may have undesirable consequences under certain circumstances: If, for example, in one of the rooms a music system equipped with reasonably good loudspeakers is playing rock music or any other bass-containing music, the neighbors in the adjacent room listen to the rock music, too – whether they want to or not, and even if the music system plays at low volume. But, as is generally known, a sufficiently high volume is what makes rock and pop music most fun…

Effective solutions are thus required to improve stud walls acoustically at low frequencies. At the IBP, a method is used that has already been examined theoretically, yet for which the practical experiences in application are still largely lacking. The method includes the weighting of the walls by a variety of point loads placed on a periodic grid. By an appropriate coordination of the construction parameters the sound insulation at acoustically critical frequencies (which in this case is the double-panel resonance of the stud wall) can be specifically improved. Compared to the currently used multiple cladding of the walls, thus a more efficient sound insulation at low frequencies can be achieved using less additional mass.

In the previous tests the masses consisted of steel sheet and were bonded to the outside of the wall (see Figure below). For practical building application other materials are intended to be used and the masses are to be fixed on the inside of the wall or integrated into the gypsum plasterboards.