Acoustic potential energy is an essential quantity that decides the magnitude of a sound perception. In active noise control, many researchers have been tried to make the 'Quiet Zone', where the acoustic potential energy is low, using multiple control sources and sensors. In contrast to the objective of active noise control, there exist situations that the acoustic potential energy needs to be increased, especially when information, not a noise, is transmitted through the sound. For example, listening music and speech recognition. In the contrary senses to the 'Quiet Zone', one can define the zone of high acoustic potential energy as an ‘Acoustically Bright Zone'. This study deals with a method to generate an acoustically bright zone using the multiple control sources.
Among the problems related to the generation of an acoustically bright zone, this study focus on two specific cases. The most significant constraint associated with the problem is, although higher input power from the control sources can increase the acoustical potential energy, that the input power is always limited. Therefore a maximization of potential energy in a desired or target zone has to be achieved under the given or allowable input power. Another problem arises when the potential energy in an unwanted zone need to be kept in low. Maximization of contrast between the bright and unwanted zone has to do with this problem.
For these two different applicative purposes, a simplified system - with pure tone sound and monopole control sources - is considered and two kinds of cost functions are defined. An eigenvalue analysis determines the optimal volume velocity distribution of the sources. This mainly constructs the theoretical basis of the proposed method. The simulation and experiments in a free field condition certainly proved the proposed method.
