Un imageur acoustique passif, la "Grande Oreille"

Abstract
The "Big Ear" is a signal processing system which permits multiple beamforming of audio signals in real time. It may be used with any kind of arrays of microphones or hydrophones and permits to "ear" a selected point of space through instructions given to the system by a microcomputer. 2000 such points can be defined in the initial phase and shift from one to another may be done in real time so that an acoustical exploration of space is achieved in a short time. An autocalibration of the system obtained from a reference source is also an interesting opportunity. Results obtained with a first realisation which may involve 32 channel arrays, are shown. Aerial and submarine signals have been treated in collaboration with O.N.E.R.A. (Office National d'Etudes et de Recherches Aérospatiales). The potentialities offered by a new system are described. It will be more powerful : 64 sources treated simultaneously from a 64 channel array. The spectral acoustical image will be achieved through an integrated Fast Fourier Transform treatment. The 64 spectral densities of the 64 sources, averaged over a duration of one second will be continuously available at the output.