A new technique has been developed to automatically detect rub defects in loudspeakers using digital processing. Loudspeakers are tested near resonance with a high level signal. The response is analyzed using an FFT and a unique post processing algorithm. A personal computer equipped with a multimedia sound card is used to generate test signals and to record the responses of loudspeaker drivers. The system is fast, reliable, economical, and inherently immune to background noises.