19.01.2010
People walking on different floor coverings are differently loud. As there are countries with regulations about this, the European organisation for standardisation, CEN, awarded a working group the task of developing a corresponding measuring and assessment procedure for walking noise.
In the Physikalisch-Technische Bundesanstalt, one scientist of which is chairing the corresponding working group, a new measurement procedure was, thus, developed which offers the following benefits:
1) Instead of taking as a basis a European standard person walking with the right shoes - who does not exist in reality anyway - the impact sound tapping machine was used as the source for walking noises. This has the considerable advantage of already being available in practically all building acoustics laboratories.
2) The very time-consuming pre-determination of the background noise of the tapping machine used (which, unfortunately, is often quite considerable and, apart from this, is also dependent on the floor covering) was replaced by a simple differential measurement in which the tapping machine 'sees' the same floor covering at its feet both times, but in which this floor covering can - because of the differently selected sample dimensions - at one time radiate airborne sound and the other time cannot.
3) The measuring must be undertaken in both rooms of a test facility for testing floors in accordance with ISO 140-1. Such test facilities, too, are already available in a large number for standard impact sound measurements in accordance with ISO 140. With this type of test facility, the laboratory-specific contribution of the concrete floor to the walking noise can then 'by the by' be replaced by the standardised values of a reference floor.
4) After all an uncertainty calculation obligatory for this procedure shows just how much the tapping machine was usable for the measurement undertaken regarding its own noise ("self noise").
The first measurements with three very different floor coverings and tapping machines ran very promisingly. As a result, not only the order which subjectively had already been felt as being 'right' was confirmed for the tested coverings - PVC floor covering, laminate flooring and carpet -, but it also turned out that the measurement results for each individual covering lay close together, even when very loud tapping machines were used (see figure 1).
The new measurement procedure is being discussed in the standardisation group at present and is intended to be tested in an intercomparison test.
Figure 1: A-weighted walking noise levels of three floor coverings measured with different standard tapping machines (TM).
Contact person:
Werner Scholl, FB 1.7, e-mail: Werner.Scholl@ptb.de