A rectangular cavity with an L/D of 5.67 was tested at Mach 1.5 with a corresponding Reynolds number of 7.35 × 10⁶/m. High speed shadowgraph movies were simultaneously sampled with dynamic pressure sensors at 75 kHz. Fourier analysis was performed on the high speed movies as well as the dynamic pressure data, which resulted in the determination of spatial and temporal characteristics of the dominant cavity frequencies in the flow field. Four passive flow control devices were tested, two of which have historically performed well at reducing the acoustic tones and broadband noise levels. The other two devices were less effective. Flow physics based on the detailed analysis of the high speed shadowgraphs and dynamic pressures sensors is presented.