<p>The supersonic mixing field induced by a novel wall-mounted cavity having a three-dimensional shape is investigated experimentally and computationally. In the experiments, the phase-averaged pressure oscillation fields are measured by using anodized aluminum pressure-sensitive paint (AA-PSP). The experimental results are compared with the computational results obtained by solving the Navier-Stokes equations. It is found from the experimental and computational results that pressure waves propagate in the cavity and that the waves act on the jet so as that it fluctuates largely. Such large fluctuation of jet is one of the primary reasons why mixing is enhanced by using the proposed cavity.</p>