On the Problematic Nature of the Excitation of Structure-Borne Sound for Test Measurements with Floors

After description of the standard impact machine for “footsteps”-measurements, it is shown that the “improvement” by using resilient layers is increased with increasing impedance of the transmitter, i. e. with increasing mass of the hammers, whereas this influence is negligible in the case of floating-floor constructions. The often repeated demand for a change of the impact machine is supported mainly by the fact that the difference between these two floor constructions is much smaller in actual footfall tests. An imitation of the “walking-noise”, however, does not only require a bigger mass but also a resilient coating of the hammers. Through this, on the other hand, stiffer floor coverings appear to be ineffective. Also the increase in weight touches on constructional limits. In any case, the non-linear overstrain due to the impact machine can be excluded by reducing the height of fall or, even better, by changing over to electrodynamic transmitters. Excitation of floors by electrodynamic transmitters through rods imitating household machines proves in theory and experiment the superiority of the floating-floor construction.