The Buzz, Squeak, and Rattle (BSR) noises coming from car body parts are often caused by defective assembly. This paper presents an in-process BSR noise detection system for car door trims. A car door trim is slowly pressed down by a pneumatic pusher, and then the acoustic signals measured right above the door trim and on the four corners of the noise detection workstation are monitored for noise source localization by the time difference of arrival method and the relative signal strengths. Finally, the energy of BSR noise is examined by the discretized frequency information of the localized signals.