Sound fields in a slightly damped rectangular enclosure under active control

Effectiveness of the global sound field control inside a slightly damped re ctangular enclosure by using the potential energy, the squared pressure and the energy density as the cost function is investigated numerically in the present study. A detailed comparison between results obtained using pressu re-squared sensing and energy density sensing is presented and the distribu tions of the zones of quiet are discussed. Three-dimensional visualization of the sound fields confirms that significant localized sound attenuation c an be achieved in specific areas even an overall amplification of total pot ential energy in the enclosure results. The present results also show the o ccurrence of the detrimental effects and spillovers under the pressure-squa red sensing, while they can be removed by using the energy density control. The energy density control results in more uniform sound fields, but is no t effective if the error sensor is located between the primary and secondar y sound sources. The present finding on producing large quiet zones using a simple system has significant implication for building noise control. (C) 2000 Academic Press.