Data on narrowband acoustic disturbances that arise in manifold pipes with one or two blind branches and in wind tunnels with an open working section are analyzed. The ranges of acoustic instability that correspond to excitation of selfoscillations in a flow in the cases mentioned are determined. The dependence of the intensity of acoustic radiation in two blind branches and in the manifold between them on the multiplicity of the length of the resonance section to the length of halfwaves of resonance frequency is considered. The possibility of attenuation of selfoscillations by organizing hydrodynamic structures that interact with formations generating acoustic oscillations is determined.