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Hi-2 Weighted Harmonic Distortion (Hi-2)

Add-on to the SPL Task and Optional Module for the KLIPPEL QC Framework

Features and Benefits

  • Fast measurement of Hi2 distortion (also called „Blat“)
  • Standardized or user defined limits
  • Compatible to DIS-Pro
  • Integrated in SPL task
  • Conform to automotive standard
  • Sensitive distortion measurement of higher harmonics

Hi-2 distortion (also called “Blat” distortion since detected defects sound like a “blat” on bass signals) is calculated from higher order harmonic distortion. Such harmonics are weighted in a special way to emphasize defect symptoms of unacceptable speaker behavior. The cause of the distortion was determined to be a rapid increase in suspension stiffness at large cone excursion.

This distortion measure is related to Rub&Buzz symptoms, which also indicates abnormal sound. However, Hi-2 distortion are characterized by lower harmonics than what Rub&Buzz distortion typically show.

The SPL Task uses a sine chirp for Hi-2 distortion measurement and can therefore measure this symptom in very short time. Hi-2 distortion may also be measured by the DIS Pro module using steady state sine tones.


Test Objects

  • Hi-2 distortion was developed for automotive woofer, subwoofer
  • applicable also to other types, especially low frequency drive units


Test Hardware 

License Dongle (USB)




Related Information

Other Modules of the R&D System

Other Modules of the QC System


Non-official standards by automotive industry