Abstract:

This reasearch is interested in the global control of free-field sound. It's aim is the development of optimal sensing systems which will maximise the amount of active cancellation possible for such a system. Traditionally when attempting active noise control on free-field sound radiation, different arrangements of pressure error sensors are used. These attempts have resulted in localised cancellation in and arround the error sensors and none or perhaps even increasing the sound levels in other regions. Since the desired locale of noise reduction can be quite large, this approach is unacceptable. What is needed is a globalised reduction in noise levels. This can only be achieved with globalised error sensing systems, such as Sound Power. Sound Intensity is gives a measure of the Sound Power and hence can be used to generate global control. The work looks at comparing a theoretical model of such a control system, with an experimental setup. By which it is hoped to show that Active Noise Control can be successfully applied to reduce free-field sound radiation.