ABSTRACT
In this chapter a third ‘general group’ of active noise control problems will be examined: that of controlling sound fields in enclosed spaces. This group of problems includes many commonly encountered systems, such as automobile interiors, aircraft cabins, ship cabins and rooms in houses. Initial consideration of active control of enclosed sound fields was undertaken in the 1950s, with the aim being to achieve both global and local sound attenuation using an ‘electronic sound absorber’ (Olson and May, 1953; Olson, 1956). This device was basically a single speaker and microphone placed in close proximity of each other, with a feedback control system that could drive the speaker to either reduce the pressure at the microphone or absorb part of the incident acoustic field. Little became of this device at its time of inception, possibly due to limitations in electronics technology.
