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Abstract

A method of pre-emphasising a signal comprises the steps of a) receiving the signal as an input; b) applying the input signal to a processing system comprising a pair of parallel signal processing paths each comprising a non-linear phase filter and a non-linearity, and a further parallel path, wherein the filters in the pair of processing paths have equal but opposite phase responses and substantially equal magnitude responses, and wherein the outputs of the parallel processing paths are combined to produce the raw pre-emphasised signal; whereby the input signal is subjected to a non-linear dynamic range compression which is phase linear. Alternatively or additionally the input signal is split into at least three different frequency bands for non-linear processing. Preferably the pre-emphasised signal is pre-corrected using an iterative system. Complementary de-emphasis systems are also described, as well as pre-emphasis and de-emphasis apparatus.

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