Binaural source location

It is shown how the coherence and phase spectra 0f signals from a closely spaced pair of microphones in the far-field can be used to compute the moments of a line distribution of arbitrarily correlated omni-directional sound radiators. This line source gives a far-field which is equivalent to that of model-scale and full-size turbojet engines in terms of measured power and cross-spectra 0f microphone signals. The necessary spectra can be computed rapidly on a small digital computer and the simplicity of the technique has meant that experiments could be performed in parallel with the usual far-field noise measurements. In this way, it has been possible t0 identify important properties of noise generation by turbojet engines at minimum cost and development and application of more sophisticated techniques has been accelerated. It is shown how the apparent properties of the source distribution may depend markedly on distance from the source to the microphones. Interpretation of results is guided by consideration of simple cases.