Comparative study of cone-shaped versus flat-panel speakers for active noise control of multi-tonal signals in open windows
Additional Publication Information
Openings on walls, such as windows or doors, facilitate the propagation of external noises to interior spaces. Active noise control is a promising technique for the reduction of low frequency noise propagating through such openings. To preserve the full functionality of the opening, especially for natural ventilation, it is required to minimize the physical size of the secondary sources. In this scenario, using compact speakers and limiting their distances from the reference microphones are critical requirements. In this paper, we present a comparative study on the noise reduction performance of an active noise control system using compact cone-shaped and flat-panel speakers in identical configurations. The performance was measured based on multi-tonal noise with frequency components below 1.2 kHz, using different setups of single reference sensor, single error sensor, and up to four secondary sources. In evaluating the measurement data, including frequency responses, harmonic distortion, radiation patterns, and noise reduction, we highlight key differences of these two types of speakers and determine their respective application contexts.