Localization of multiple acoustic sources in a room environment

Combustion systems results in high pollution and low performance due to lack of uniform thermal and chemical behavior in the entire reactor zone. Localization of multiple acoustic sources using an array of microphones and time difference of arrival (TDOA) method is examined. Adaptations of such a scheme into high speed jet flows, combustors or reactors can help assist in the identification of local acoustic sources in a system to seek improved performance of the system. Linear microphones can be used for acoustic source localization in a practical room environment using time delay estimation. Hyperbolic position algorithm based on TDOA provides good localization of a single acoustic in both two dimensional and three dimensional space. The time delay between the signals acquired by two microphones is obtained from maximum of cross-correlation between the two signals. Noise and reverberation effects can introduce ambiguity in the time delay estimation from multiple peaks in the delay estimator. In addition directional incidence from multiple sources can result in cross talk between different sources to degrade localization accuracy. CPSP (Cross-power spectral phase analysis) is examined here for localization of multiple sound sources present in a room environment. The CPSP method localizes a sound source as a crossing point of sound directions estimated using different microphone pairs but it degrades due to cross-correlation between different sound sources. A new method based on averaging of CPSP coefficients has been examined here to reduce the directional ambiguity of the wave front direction angle of multiple sound sources. Experiment results in a real room environment validated the accuracy and precision of the above method for the estimation of directions of multiple sound sources. Experiment results also showed that noise and reverberation effects can be incorporated by averaging CPSP data over larger pairs of microphones. Subsequently localization of multiple sources was accomplished in a room environment by using hyperbolic position estimation. These results provide a foundation to develop methodologies for smart, low noise, low pollution and highly efficient combustors and gasifiers through seeking uniform reaction field in the entire reaction zone.