Structure-borne Sound Sources in Buildings

It is more difficult to solve structure-borne noise problems, including those in buildings, than airborne noise problems. One reason for this is that there is not an agreed approach; in particular, on how to describe machines as vibrational sources. A review is given of proposed approaches to the characterisation of machines as structure-borne sound sources. It is demonstrated that both a machine's activity and its dynamic characteristics are needed to properly describe its ability to emit structure-borne sound. It is also demonstrated that emission and source characterisation are distinctly different. In addition, at present, there does not appear to be a compromise possible between a proper characterisation and methods which are simple and practical and it is argued that present attempts to produce standards are premature. In the short term, a measure of source activity such as free velocity may be acceptable. A source descriptor is described which is a proper characterisation but requires the acquisition and processing of much data. It would appear worthy of development but the challenge remains to present product data in a simple and practical way.