A summary of recent experimental research efforts at Syracuse University aimed at active flow control is presented with emphasis placed on the development of low-dimensional tools to facilitate closed-loop control. Results indicate that the near-field pressure in a Mach 0.85 high Reynolds number jet is low dimensional and it is primarily the azimuthal near-field pressure mode 0 that correlates with the acoustic field. The turbulent velocity field in the high-speed jet can also be estimated from the near-field pressure, and is used herein to predict the far-field acoustics. Tools being developed to improve recent successful, high Reynolds number, closed-loop flow control in a NACA 4412 airfoil are also discussed. Together, these results set the framework for active flow control in the high-speed jet with the goal of reducing jet noise. Key wordsFlow control-jets-coherent structures-aeroacoustics-flow separation-low-dimensional techniques.