Abstract
The Lighthill theory has been extended so that it may be used to determine the flow noise induced by a turbulent boundary layer over a plane homogeneous flexible surface. The influence of the surface properties and the mean flow on the sound generated is brought out explicitly through the use of a Green function. It is found that there is an analogy between the sound generated by turbulence and equivalent sources placed between a surface with the same compliance as the physical surface and a hypothetical vortex sheet positioned at the outer edge of the boundary layer. This analogy is used to determine the spectrum of the surface-pressure fluctuations under statistically stationary turbulence. The form of this wall-pressure spectrum is investigated in detail for three particular types of surface: rigid surfaces, bending plates and sound-absorbent liners.

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