Application of noise source identification techniques to consumer products with illustration on a dishwasher, a washing machine, and a copying machine

While many classes of consumer products represent stationary noise sources, others do not, meaning that the simpler methods of noise source identification such as intensity mapping cannot be applied to them. In this situation, it becomes necessary to turn to the array methods, namely Transient Near-field Acoustical Holography, (Transient NAH, also known as Non-stationary Spatial Transformation of Sound Fields), and Transient Beamforming. Transient NAH is better for identifying low frequency noise sources, while Transient Beamforming is more suited to identifying those at higher frequencies, and both of these methods can be used on non-stationary noise sources. One of the latest techniques is to combine the two methods using the same array to identify noise sources over a wide frequency range. Both methods are described with Transient NAH being illustrated in measurements on a dishwasher operating in an unloaded and a loaded condition, Transient NAH and Transient Beamforming being illustrated in measurements on a washing machine, and combined Transient NAH and Beamforming being illustrated with measurements on a copying machine.