As our age becomes more industrialized, the problems of quieting machinery and appliances—whether they occur in industry, office or home—become more numerous and more difficult. The economy of using improved research methods and competent scientific personnel is emphasized. Determination of qualitative data (source of energy, source of radiation, relative spectral distribution, relative intensity of frequency peaks, etc.) is usually more important than spending excess time obtaining quantitative data (precise sound intensity, exact frequency spectrum, percent harmonic content, etc.). The importance of analysis of sound energy sources, sound radiation sources, and coupling factors between them will be emphasized. A system of analyzing noise problems, by schematic diagrams giving the energy flow between sound energy sources and the surrounding propagating medium, will be outlined and illustrated by actual data from typical research problems.