1. A method comprising: transforming a signal based at least in part on a wavelet transform to generate a transformed signal, generating a first wavelet scalogram based at least in part on the transformed signal, detecting ridges within a region of the first wavelet scalogram, determining one or more parameters for the detected ridges, determining a ridge density distribution function based at least in part on the one or more parameters, and selecting a ridge based at least in part on the ridge having a scale corresponding to a maximum value of the ridge density distribution function.