Blind source localization in a room based on wavefield separation

Narrowband localization of sources in a room is a challenging problem because of the multiple reflections off the walls. Recently, we have been developing methods to localize monochromatic sources within an array of a few tens of microphones, without any knowledge on the physical properties of the room. To that end, we use a wavefield dereverberation approach in which the diffuse part is canceled, thanks to a projection operator built from a plane wave basis. However, this basis requires that no heterogeneities are present in the space of interest between the microphones. To overcome this limitation, in the case of an heterogeneous space, we show that a new projection operator can be experimentally built from a set of measurements of the responses between the microphones and some sources. This projection operator removes the reverberation, and can be used as preprocessing to locate the sources despite the heterogeneities, for instance by using classical beamforming processing. The method is first validated with numerical simulations. Then, experiments are performed in a large room, with an array composed of 100 microphones. A source, emitting at 500 Hz, can be located close to a strong reflector with an accuracy of about 10 cm.