Balazs P.

This paper presents an overview and summary on the mathematical background for time-frequency masking filters based on the concept of 'frame multiplier'. Gabor multipliers are a current topic of research, known in signal processing as Gabor filters. Frame multipliers are a generalization of this type of time variant filters to frames without further structure. After the analysis, before the synthesis the coefficients are multiplied by a fixed pattern, the so called symbol. Basic results, such as the dependency of the operator on the symbol, are given. The paper investigates Irregular Gabor frames. In particular the results on irregular Gabor filters are proved such as the continuous dependency of Gabor filters on the symbol, the lattice and the windows. An algorithm is presented for the approximation of arbitrary matrices by irregular Gabor multipliers and is compared to the regular algorithm. In view of applications the finite-dimensional discrete case is important. A proposal is given how to approximately invert the Gabor frame operator (for regular lattices) numerically efficient by using 'double preconditioning'. Finally a concept is presented how to implement a filter, which approximates the simultaneous and temporal masking known in psychoacoustics. As the linear frequency scale (in Hz ) is not applicable to human perception, Bark scale has been introduced, consequently this filtering can be seen as an irregular Gabor multiplier with adaptable mask. The current paper reports on work in progress and presents some selected results only. An outlook on further results is given.