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Multi-Tone Distortion (MTD)

Optional Modules for the KLIPPEL QC Framework

Features and Benefits

  • Multi-tone broad-band stimulus (music-like)
  • Acoustic „finger print“ testing of speakers and audio systems (max SPL & distortion)
  • Fundamental, level and transfer function
  • Multi-tone distortion (MD) includes all distortion (HD, IMD)
  • Relative MD and Total MD Ratio for simple limit setting
  • Robust towards room influence
  • Compliant to IEC60268-21
  • Dedicated to fast-end-of-line testing
  • Ensures overall consistency of production

The Multi-Tone Distortion (MTD) task is an add-on to the QC end-of-line test system. Closely related to the MTON module with focus on R&D applications, the MTD is based on multi-tone test signals.

In contrast to pure sinusoidal sweep excitation (such as SPL Task), multi-tone stimuli do not only excite harmonic distortion (HD) but also intermodulation distortion (IMD). Therefore, multi-tone distortion provides a much more comprehensive distortion pattern than harmonics alone. Due to the sparse broad band excitation, it is not always possible to identify distinct root causes and symptoms in multi-tone distortion, but it provides a more realistic distortion finger print than pure HD and IMD tests since operation conditions are closer to the final application with music. Therefore, the MTD is highly valuable to verify audio quality and max SPL handling in quality control.

Test Objects

  • Any (except Suspension Parts)


Test Hardware 

License Dongle (USB)





dB-Lab Operation Template: QC Multi-tone Distortion (MTD)

Related Information

Other Modules of the QC System

Related Products

Literature and Papers


International Electrotechnical Commission
IEC 60268-21 Sound system equipment - Part 21: Acoustical (output-based) measurements