Analysis of the global reduction of broadband noise in a telephone kiosk using a MIMO modal ANC system

Optimizing a Multi-Channel ANC System for Broadband Noise Cancellation in a Telephone Kiosk Using Genetic Algorithms

“…The speaker emits colored noise in the frequency range from 50 Hz to 300 Hz, and we intend to minimize the mean of the acoustic potential energy in this frequency range. A thorough modal analysis of this enclosure was performed in a separate work [12] in which the range of the frequency for which global reduction of broadband noise is possible has been determined. It has also shown that the position of loudspeakers and microphones has substantial effect on the maximum achievable reduction of acoustic potential energy, and the corner of the enclosure will not be a good choice for positioning the loudspeakers because of existence of degenerate modes.…”

“…A common way to reduce such environmental noise is to place the phone set in an enclosure; However, since the main components of street or industrial noise cover frequencies from below 100 Hz to over 500 Hz, active noise control (ANC) systems are a potential solution to improve the quality of communication in telephone kiosks by reducing the noise inside the cabin. The analysis and feasibility study for global reduction of broandband noise in such an application is studied by the same authors [12], and showed that due to the existence of degenerate modes the control action is complicated and needs more considerations. On the other hand since ANC systems are application specific, they should be optimally designed for each application and the most important parameters that must be optimized are positions of loudspeakers and microphones (Fig.…”

GA-based optimization of a MIMO ANC system considering coupling of secondary sources in a telephone kiosk

“…In these studies it is also assumed that the dimensions of the enclosure are not multiple integers of each others. The modal analysis of an enclosure having this property but without the assumption of coupling among secondary loudspeakers is studied in [22]. This enclosure which is a model of a telephone kiosk is shown in Fig.…”

“…The major differences of this work with the previous ones in this area are: 1. Referring to the analysis and feasibility study performed in [22] for global reduction of broadband noise inside the telephone kiosk selected for this study, it is shown that due to the existence of degenerate modes (different mode shapes with the same resonance frequencies) the placement of sensors and actuators needs more considerations. 2.…”

Analysis of the behavior of coupled loudspeakers in a MIMO ANC system in an enclosure

“…In [12,13] it is proposed to locate the control sources and error sensors at the corners of the enclosure for global control of lowfrequency noise using the squared-pressure method. However, the analysis in [14] shows that if the dimension of the enclosure are integer multiply of each other, the corner placement of secondary sources will not give the best results for global noise control.…”