Methods and arrangements for processing a signal using a digital processor having a given word length. The signal is pre-processed using a pre-processor which reduces the word length and performs an operation which is invariant with respect to a process being performed by the digital signal processor. This means that if the pre-processor operated with infinite accuracy, it would have no effect on the subsequent process. If such a pre-processor operates with infinite accuracy, it will reduce the guantization noise. In the digital signal processor, the pre-processed signal may be transformed into frequency coefficients which are normalized directly thereafter.