Abstract: A method of processing a signal comprises receiving a signal, filtering the signal with a plurality of band pass filters, each band pass filter having a Q factor of at least 1/v2, and extracting data from the output of the filters. The primary data extraction comprises identifying local peaks in the output of the filters, each local peak being a local peak in both the time and frequency directions. The method advantageously further comprises executing a curve fitting procedure, the output of which procedure comprises curve data defining a curve that at least approximates to a portion of the extracted data. The method can further comprise varying the Q factor of at least one band pass filter as the signal is filtered.