SIFT (Scale Invariant Feature Transform) is a very popular local feature descriptor, and is widely used in computer vision applications. Likewise Harris corner detector is also useful for feature extraction from images. I am looking for similar feature descriptors that can be used to match two 1D signals like speech, ECG etc. I am analyzing electromagnetic signals, and have noticed that some parts of the signal contain "interesting" features that is good for matching or pattern recognition (even visually), while some other parts don't contain so much discernible patterns. Is there any algorithm that can quantify or identify local features in 1D signal?