A typical problem in production is dealing with the effect of tolerated distortion symptoms in DUTs such as economic products. These high frequency components degrade the sensitivity of the standard Rub & Buzz detection due to masking effects. Exploiting the highly similar symptoms of consecutive DUTs in a production process, an adaptive process models the regular distortion as produced by any good unit. The active cancellation of the regular distortion reveals tiny defect symptoms  clearly  that are  otherwise  completely  masked. Even  if  these  subtle  defects  are  not  audible  during  production, they may become worse over time and cause expensive damage to the final product.

• Improves standard Rub & Buzz analysis
• Defect detection beyond human hearing
• Extends analysis bandwidth for defect symptoms
• Attenuates high-order harmonic distortion
• Unmask subtle defect symptoms

This example shows a loose particle producing an inaudible click which is completely masked by the regular distortion generated by accepted motor and suspension nonlinearity. These defects can be detected by MHT before getting worse, becoming audible and causing field rejects.