Identification of noise sources in notebook systems using acoustic holography.
Jose Cordova · The Journal of the Acoustical Society of America · 2010
The acoustic noise generated by notebook computers is an important quality aspect for consumers. Cooling fans, hard disk drives, and optical disk drives are the main sources of noise in these types of systems. Standard measurement techniques such as sound power or sound pressure are used for measuring the overall acoustic energy generated by a device or the sound pressure at a specific point in space respectively, but give us little information of the location of the noise sources and the transmission paths such as noise leaks. This paper outlines the use of acoustic holography for the identification of noise sources and transmission paths in notebook systems. The setup consists of static reference microphones and a roving array of microphones used to scan the surface above a notebook system. With acoustic holography software, the noise field is constructed and back propagated to the surface where the location of the main noise sources is identified. 3-D iso-surface sound pressure maps and sound intensity maps (passive and reactive) are shown for notebook computers with different airflow system impedances. The technique is validated by reconstructing the radiation characteristics and obtaining the location of elementary monopole and dipole sources.