Measuring Ln without using a tapping machine?

We propose an alternative method for measuring Ln which we suggest will make field testing of buildings easier and more attractive to do. Although field testing is essential for quality control during construction, and to demonstrate conformity with building code requirements, it has challenges which make it unpopular. In particular the tapping machine’s fixed power-output and hence Ln’s lack of immunity to interference from background noise rules out its use during construction. In addition the formal measurement procedure can be time consuming, it involves the cost of a tapping machine and it requires a specialist acoustical engineer. In our method Ln is inferred from a measurement of the airborne sound insulation (R) by using a relationship between R and Ln. R can be measured by either using a high power source, or by coherent averaging of a deterministic signal, hence background noise interference is obviated. An impact on the floor is still necessary to determine the effect of its actual impedance. However our method uses a single hand-held hammer and infers the effect of impacting with the tapping machine by measuring the reaction force on the hammer.