A common method of noise control is the implementation of passive transmission loss enclosures. An acoustical enclosure surrounds a noise source for the purpose of interrupting the noise transmission path. The effectiveness of these enclosures is, however, limited by various drawbacks. These drawbacks include leaks in the enclosure walls, transmitted vibrations to the enclosure due to physical coupling, and the limited reduction of noise at low frequencies. Recent advances in active control have shown the potential for applying some of this technology to passive acoustical enclosures to improve their performance. / Master of Science