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A method has been developed for rejecting transducer flow-noise interference. The method makes use of coherence-function relations between simultaneous pressure measurements at three transducers in the signal field and extracts from the flow-noise background the power spectrum of the signal as received at each transducer. The signal in question can be periodic or stationary random. The coherence function relations are derived on the basis of a multivariate, random-process model. The theory indicates that for a single source or for a group of completely coherent sources, the three transducers can be placed at arbitrary locations in the signal field. For a group of sources that are not completely coherent, the transducers must be located close together relative to the distance from the group. In any case, however, the flow noises at the transducers must be mutually independent. Successful results were obtained in laboratory tests of the method. In these tests a 10–15-dB reduction in flow-noise interference was attained. The method can also be used to reduce other types of noise such as instrument electronic noise.
J. Y. Chung (Mon,) studied this question.