1. A speech recognition system for recognizing speech, the system comprising: one or more processors; a local-scale decoder operating on the one or more processors and generating local-scale soft information from a speech signal; a first extrinsic information extractor operating on the one or more processors; a second extrinsic information extractor operating on the one or more processors; and a broad-scale decoder operating on the one or more processors wherein: the broad-scale decoder receives the local-scale soft information; and generates broad-scale soft information based on the local-scale soft information, wherein the local-scale decoder and the broad-scale decoder further perform one or more turbo iterations, at least one of the turbo iterations comprising: the second extrinsic information extractor scaling extrinsic probabilities from the local-scale soft information and feeding back to the broad-scale decoder only the local-scale soft information that was not previously exploited by the broad-scale decoder; the first extrinsic information extractor scaling extrinsic probabilities from the broad-scale soft information and feeding back to the local-scale decoder only the broad-scale soft information that was not previously exploited by the local-scale decoder; the local-scale decoder updating the local-scale soft information based on the broad-scale soft information; and the broad-scale decoder updating the broad-scale soft information based on the local-scale soft information, wherein a plurality of hard symbol decisions are generated from one of the local-scale and the broad-scale soft information.