Noise source localisaton in a car environment

Spurious noise (rattles, squeaks, etc) in the interior of car cabinets can be annoying, distractive and
indicative of potential performance problems. Fault finding these problems can be difficult since the
fault is intermittent and may not necessarily happen under test conditions. A 3 channel system that
can record the fault and indicate its location within the cabinet is presented here. The system
consists of a coincident microphone array that measures acoustic particle velocity along two
orthogonal axes at its location. Detection and direction of noise can be obtained in real time or
during post-processing using advanced signal analysis methods. Measurements inside a vehicle
show that the very reflective nature of the sound-filed inside a car cabinet present a major challenge
and that a combination of advance techniques from diagnostics engineering and room acoustics are
required to reliably indicate the direction of the annoying sound.