This paper describes an automatic computer-controlled acoustic resonance detection workbench for high-intensity-discharge (HID) lamps. The detection method is based on optical measurements of the discharge arc path. With the aid of a dual lens projection system, relative light intensity measurements at different points of the arc are guided by fiber optic to a photodiode array. These measurements are statistically analyzed to identify when acoustic resonance occurs. Experimental results confirm this method to be a valuable tool to automatically obtain an acoustic-resonance-frequency map for HID lamps.