The document describes a procedure for the systematic evaluation of noise-emission values for the determination of a functional relation between the performance of a machine, in terms of a characteristic machine parameter, and its noise emission. The general procedure is also applicable to other kinds of emission. The following terms are defined: family of machinery or equipment, measured noise-emission value, declared noise-emission value, characteristic machine parameter, noise-control performance, cumulative frequency of noise-emission values, L-lines.