Abstract: A signal adaptive processor for detecting and identifying specific sound signals that are emitted by relatively moving or at rest sources in noisy environments. The system can provide an early warning system to alert vehicle operators of the presence of emergency vehicles which emit audio warning signals to indicate the type of vehicle and the direction form which it is coming. The processing technique used here is similar to some word-spotting algorithms used in recognition of specific words in continuous speech, however the algorithm has been modified by the inventors to meet the particular characteristics of the specific sounds. The algorithm is also enhanced by a novel adaptive filtering means which identifies the background noise features and then filters it out before extracting the features of the sound in the incoming signal stream. This feature is essential to ensure reliable operation in such noisy environments such as streets and highways.