A method and apparatus are provided for reducing a channel length. The method implements a channel-length reduction filter that takes into account a pulse response of the channel. The method includes the following steps: cutting the filter into at least one first and one second portion; optimizing said first portion of the filter according to a first criterion in order to output a first set of filtering coefficients; reducing the length of the channel by optimizing said second portion of the filter according to a second criterion different from the first one and based on the first set of filtering coefficients of said first portion of the filter in order to output a second set of filtering coefficients.