A system for inspecting spray nozzles includes a nozzle operatively connected to a source of pressurized liquid for issuing a spray from the nozzle. The system also includes a sensor positioned to detect frequencies of resonant modes in the spray. The nozzle and sensor can each be mounted to a spray test booth. A method of inspecting a spray nozzle includes issuing a liquid from a spray nozzle as a spray and using a sensor to detect frequencies of resonant modes in the spray. The sensor can include a diaphragm and detecting frequencies can include impinging at least some of the spray on the diaphragm, and monitoring vibrations of the diaphragm.