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In recent years, the perceived quality of powered seat adjusters based on their sound during operation has become a primary concern for vehicle and seat manufacturers. Historical noise targets based on overall dB(A) at the occupant's ear have consistently proved inadequate as a measure of the sound quality of a seat adjuster. Significant effort has been devoted to develop alternative sound quality metrics that can truly discriminate between “good” and “bad” seat adjusters. These new metrics have been successfully applied for some years by product development engineers in test labs. However, in the assembly plant the sound quality of the seat adjuster is still assessed subjectively by an operator at the end of the assembly line. The main problem with this approach is not only the lack of consistency and repeatability across large samples of seat tracks, but also the fact that the only feedback provided from the end-of-line to the product development team is of subjective nature.

Two years after the start of production, some members in a family of power seat adjusters developed an intermittent loud squeal sound when operated in the vehicle. An exhaustive and comprehensive engineering analysis identified the noise source to be primarily a single component in the seat track which was excited under specific conditions to vibrate in its free - free natural resonant frequency mode. The component was identified as the horizontal lead screw which vibrated under stick-slip principles against mating hardware. The noise was not reproducible in any consistent way; therefore, it was not readily detectable with 100% serial testing. Several solutions were enacted for controlling the problem in the short term while an investigation to the root cause was completed. Three long term solutions which addressed the root cause were pursued in parallel up to the production release of the best solution.