IrrelevanceMask: Mathematical Foundation of the Irrelevance Model


An irrelevance algorithm based on simultaneous masking is implemented In STx. In the years following its first development by Eckel, the efficiency of this algorithm has been clearly shown. In this project, this irrelevance model will be based on modern mathematic and psychoacoustic theories and knowledge.


This algorithm can be described as a Gabor multiplier with an adaptive symbol. With existing related theory, it becomes clear that a high redundancy must be selected. This guarantees:

  • perfect reconstruction synthesis
  • an under-spread operator for good time-frequency localization
  • a smoothing-out of easily detectable quick on/off cycles

Furthermore, it can be shown that the model used for the spreading function here is mathematically equivalent to the excitation pattern.


This algorithm has been used for several years already for things such as:

  • automobile sound design
  • over-masking for background-foreground separation
  • improved speech recognition in noise
  • contrast increase for hearing-impaired persons


  • G. Eckel, Institut für Elektronische Musik und Akustik, Graz


  • P. Balazs, B. Laback, G. Eckel, W. Deutsch, "Introducing Time-Frequency Sparsity by Removing Perceptually Irrelevant Components Using a Simple Model of Simultaneous Masking", IEEE Transactions on Audio, Speech and Language Processing, Vol. 17 (7) , in press (2009) , preprint


This project ended on 01.01.2010, and leads to a sub-project of the 'High Potential'-Project of the WWTF, MULAC.