Effect of impinging plate geometry on the self-excitation of subsonic impinging jets

► Effect of plate geometry on subsonic impinging jet tones was studied. ► Feedback path of subsonic impinging jet tones was examined. ► No effect of plate diameter on both modes of impingement tones. ► A new type of tones is observed for the plate with co-axial hole for Mj⩾0.9. ► Major acoustic feedback path to the nozzle exit is inside the jet.